Skin reflectance image correction in biometric image capture

ABSTRACT

In examples, a relative skin reflectance of a captured image of a subject is quantified. Based on the relative skin reflectance, the captured image is determined as suitable or not suitable for biometric identification. When the captured image is determined not suitable, a remedial capture setting is calculated and provided to an image capturing resource. Another captured image of the subject, captured under the remedial capture setting, is received from the image capturing resource. The relative skin reflectance of the another captured image is quantified and based thereon, there is a determining of whether the another captured image is suitable or is not suitable.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application No. 62/983,206, filed Feb. 28, 2020,entitled “Quantification of Phenotypes in Biometric Image Capture,”which is incorporated by reference in the entirety.

STATEMENT OF GOVERNMENT SPONSORSHIP

This application is based on research performed under funding from theU.S. Department of Homeland Security under contract numberW911NF-13-D-0006-0003. The Government has certain rights in the subjectmatter of this disclosure.

FIELD

The application relates generally to biometric identification.

SUMMARY

A system for the quantification of phenotypes in received capturedimages and remediation of image capture, for biometric matching, mayinclude a processing system having a hardware processor configured toperform a predefined set of basic operations by loading correspondingones of a predefined native instruction set of codes, the predefinednative instruction set of codes constituting a set of instructionsselectable for execution by the hardware processor. The system mayinclude a memory accessible to the processing system, and may include acommunication controller, under control of the processing system,adapted to receive an indication that a first relative skin reflectancevalue derived from a first image of a subject is outside of apredetermined range. The system may include, stored in the memory, animage processing logic and an image capture logic. The image processinglogic may comprise a respective sequence of instructions selected fromthe predefined native instruction set of codes of the hardwareprocessor, adapted to calculate an adjustment of one or more conditionsfor capture of a second image of the subject, as a remedial capturesetting. The image capture logic may comprise another respectivesequence of instructions selected from the predefined native instructionset of codes of the hardware processor, adapted to capture the secondimage of the subject under the remedial capture setting. The imageprocessing logic may be further adapted to derive, from the secondimage, a second relative skin reflectance value for a face of thesubject, and to determine whether the second relative skin reflectancevalue is between a floor threshold and a ceiling threshold.

A method for quantifying of phenotypes in received captured imagescapture, for remediation of image capture, for biometric matching mayinclude identifying that a first relative reflectance value, derivedfrom a first image of a subject, is outside of a predetermined range ofreflectance and may include, based at least in part on the identifying:calculating a remedial capture setting, and communicating the remedialcapture setting to an image capturing resource. The method may furtherinclude, upon receiving a second image of the subject, captured by theimage capturing resource under the remedial capture setting, derivingfrom the second image of the subject a second relative reflectancevalue, the second relative reflectance value being for at least aportion of an image of the face of the subject, and determining whetherthe second relative reflectance value is within a window of suitablereflectance values.

Other features and aspects of various embodiments will become apparentto those of ordinary skill in the art from the following detaileddescription which discloses, in conjunction with the accompanyingdrawings, examples that explain features in accordance with embodiments.This summary is not intended to identify key or essential features, noris it intended to limit the scope of the invention, which is definedsolely by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The attached drawings help explain the embodiments described below.

FIG. 1 illustrates an example operating environment for capture ofimages, in systems and methods in accordance with one or moreembodiments.

FIG. 2 illustrates an example image capture of a generic subject person,for description of various features in systems and methods according toone or more embodiments.

FIG. 3 shows a flow diagram of operations in a process of quantifyingreflectance of captured images, with threshold qualified biometricmatching, for systems and methods according to one or more embodiments.

FIG. 4 shows a flow diagram of operations in a process of quantifyingrelative reflectance, for systems and methods according to one or moreembodiments.

FIG. 5 illustrates an example distribution of lighter and darker regionson a face portion of a captured image in systems and methods accordingto one or more embodiments.

FIG. 6A and FIG. 6B show examples of three-rectangle feature operationsin a face detection.

FIG. 7 shows a flow diagram of operations in an implementation ofdividing a facial region into facial pixels and remainder pixels, inprocesses for quantifying relative reflectance in systems and methodsaccording to one or more embodiments.

FIG. 8A shows an example face boundary on a captured image, in a processof separating of a facial region into facial pixels and remainderpixels; and FIG. 8B shows a zoom-out from the FIG. 8A view.

FIG. 9 shows a flow diagram of operations in a process selecting facialskin pixels from facial pixels, for processes in quantifying relativereflectance in systems and methods according to one or more embodiments.

FIG. 10 illustrates example operations in luminance-based outlierremoval in selecting facial skin pixels, for processes in quantifyingrelative reflectance in systems and methods according to one or moreembodiments.

FIG. 11 shows a flow diagram of operations in an obtaining a mean valueof selected background pixels, for processes in quantifying relativereflectance in systems and methods according to one or more embodiments.

FIG. 12 illustrates examples of obtaining representative backgroundpixels and background averaging, for processes in quantifying relativereflectance in systems and methods according to one or more embodiments.

FIG. 13 shows a flow diagram of operations in a process of quantifyingreflectance of captured images, with threshold qualified biometricmatching and selective remediation according to one or more embodiments.

FIG. 14 shows a flow diagram of operations in a process of biometricidentification and access control, with image reflectivenessthresholding, in systems and methods according to one or moreembodiments.

FIG. 15 shows a flow diagram of operations in a process of quantifyingreflectance of captured images and of remediating image captureaccording to one or more embodiments.

FIG. 16 illustrates an example operating environment for capture ofimages in accordance with one or more embodiments.

FIG. 17 illustrates, in simplified schematic form, a computing system onwhich aspects of the present disclosure can be practiced.

FIG. 18 shows distributions of variables self-reported by test subjects.

FIG. 19 shows a functional schematic of an example test system.

FIG. 20 shows an example logic flow diagram of a process for extractingskin (R, G, B) color values from enrollment images.

FIG. 21 graphically depicts example biometric evaluation results.

FIG. 22 graphically depicts other biometric evaluation results.

DETAILED DESCRIPTION Overview

Various embodiments, configurations, features, and operations aredescribed using airports as an example environment, and securityscreening with image capture and biometric image matching as an exampleapplication. Ronald Reagan Washington National Airport (referred tohereinafter as National Airport) provides a concrete use case as but oneexample environment. It will be understood though, that airports areonly an example environment for practices according to disclosedembodiments.

Features of an example will be described assuming an embodiment inaccordance with this disclosure connects to and interfaces with one ormore security screening resources at National Airport. It will beassumed that the embodiment connects to and interfaces with an imagecapture kiosk and a biometric matching resource. The example will assumeMark as a subject, and that Mark has arrived, via ground transport fromhis residence in Washington D.C., at National Airport. It will beassumed that Mark, prior to checking his luggage, stops at a biometricimage capture station.

The biometric image capture station captures an image of Mark. Thestation sends the captured image of Mark to a phenotype quantificationsystem, configured to quantify a skin reflectance value of Mark's facialskin, as captured in the image. The phenotype quantification systemprocesses the captured image and determines a quantified skinreflectance value for the facial skin in the image. The phenotypequantification system can compare the quantified skin reflectance valueto one or more qualification thresholds. In one or more embodiments, thecaptured image is input to the biometric matching system only when thequantified reflectance meets the one or more thresholds. Embodiments canbe configured to apply remediation processes when the captured imagesquantified reflectance does not meet thresholds, before the image isinput to the biometric matching system.

The qualification thresholds have been determined from particularanalyses as obtaining, when applied as a qualifier for captured imagesto be used for biometric matching, a statistically significantimprovement in biometric image matching performance.

Embodiments

FIG. 1 illustrates an implementation of one image capture system 100(hereinafter “system 100”). This system may capture images and mayinterface and operate with systems and methods in accordance withvarious embodiments. System 100 can include a light source 102, adigital camera 104 and, optionally, a background surface 106, such as aneutral background (gray). In an aspect, the digital camera 104 canfeature an adjustable spectral sensitivity, configured to receive aspectral sensitivity command, such as the example STY-CMD command shownin FIG. 1. Control logic for generating STY-CMD or an equivalentspectral sensitivity command is described in greater detail below, andin reference to FIG. 17.

The light source 102 can be configured to illuminate a subject 108 whenpositioned, e.g., standing or sitting, in what may be a designated areaDA in front of the background surface 106 if used. The center of thesubject's face 110 is at height H1. The height H2 of the digital camera104 can be adjusted, for example, to be the same as height H1.

System 100 can provide a constant medium (e.g., air) light path from thelight source 102 to the subject 108. Additionally, or alternatively, thesystem 100 can provide a light diffuser 112 between the light source 102and the subject 108. The light diffuser 112, if used, may be implementedby an adjustable light diffusion apparatus, e.g., a commercialoff-the-shelf (COTS) adjustable diffuser such as is available fromvarious vendors.

Implementations of the light source 102 can be, for example,controllable LED lights or other lights. The light source 102 is notnecessarily a system 100 dedicated resource, as one or moreimplementations of system 100 can utilize, but can be switched on or offor adjusted to take into account ambient light as part or all of thelight source 102.

FIG. 1 shows a single light source 102 but that is not intended as alimitation on quantity or positioning of light sources. Light source 102can be among a plurality of light sources, which can be at respectivepositions relative to the subject 108. The plurality of light sources,if used, can be of a common type, or one or more of the light sourcescan be of one type and another one or more can be of another type. Inimplementations using multiple light sources 102, one or more of thelight sources may be provided with a light diffuser, such as the lightdiffuser 112.

In another adaptation the system 100 can use illumination outside thevisible light spectrum, e.g., ultraviolet (UV) light, as a supplement toor as an alternative to visible light. In another adaptation, the system100 can use, instead of or in addition to the digital camera 104, animage capture device other than a camera.

In an operation, light incident on skin surfaces of the subject's face110 and on other surfaces of the subject 108, and on background surface106, is reflected back as reflection rays 114, which are captured by thedigital camera 104 or the like to form a digital image.

In an implementation, the digital camera 104 can be integrated in akiosk, and functionality of the kiosk can include, in addition tocapturing an image of the subject 108, accepting an identificationcredential from the subject 108. Example identification credentialsinclude electronic credentials such as a mobile driver's license (mDL)that contains a reference image and contains, in some embodiments, otherbiometric information for an asserted identity. The electroniccredential can be provisioned to a mobile device such as a smartphone orthe like. The kiosk can be configured to receive the reference imageand, for example, other biometric information, and in one or moreembodiments the received reference image from the identificationcredential can be used for comparison against the captured image, asdescribed in greater detail in later sections. Contemplatedimplementations also include the kiosk being configured with a scannerto receive, for example, a visible reference image from a physicalidentification card, such as a physical driver's license.

FIG. 2 illustrates visible aspects 200 of one generic subject person, asmay be a subject 108 for image capture, for post-capture phenotypicquantification processes, and other processing in accordance withvarious disclosed embodiments.

Some example implementations of computer-implemented methods inaccordance with one or more embodiments for calculating a relative skinreflectance will now be described. Reference will be made to devices,systems, hardware, software, and other phenotypic information that canbe used in conjunction with or independent of the described methods andsteps.

Practices in accordance with disclosed embodiments can includemodifications, variations, adaptations, combinations, andre-arrangements of described examples. For example, a system mayimplement other phenotypic measures to determine whether acquired datais suitable for subsequent use.

Example capture devices are operational to electronically obtain one ormore images of an individual's face, e.g., facial features, or the likethat are usable to uniquely identify the person based on biometricinformation obtained from them. Though devices operating in the visibleportion of the electromagnetic spectrum are discussed, other energyranges, e.g., infrared, UV, are contemplated as well. In accordance withthis disclosure, different energy ranges may be implemented incombination or for different purposes. For example, a visible lightdigital camera can be used to acquire an initial image while anotherdigital capture device (or a portion of the device) can be used tocapture an additional image. These approaches may be implemented for avariety of purposes, such as to promote equitability across differentpopulations.

In an example, a digital camera can capture an electronic image thatincludes a representation of a human face. The digital camera cancommunicate the data forming the captured image to a computing systemthat can be configured to calculate the skin reflectance on the facialportion of the image and output an indication of whether the skinreflectance is or is not within a predetermined range of acceptability.It will be understood that “predetermined range” may be alternativelyreferred to as “range of acceptability,” “given range,” “predeterminedrange of acceptability,” “acceptable range of reflectance,” and soforth. For brevity, “acceptable range of reflectance” will be used insubsequent paragraphs.

The acceptable range of reflectance may be based on various factors.Example factors can include, but are not limited to, the particularfacial identification algorithm(s) that will receive the captureddigital images. As an illustration, one acceptable range of reflectancecan be assigned to or tailored to a first list of biometricidentification algorithms, and another acceptable range of reflectancecan be assigned to or tailored to a second list of biometricidentification algorithms. In accordance with some embodiments, systemsand methods can include a dynamic adjustment of the acceptable range ofreflectance.

FIG. 3 shows a flow diagram of operations in a process 300 for receivinga captured image of a subject, quantifying the relative reflectance ofthe image's facial skin regions, and qualifying the reflectance againsta reflectance threshold. The process 300 also forwards captured imagesmeeting the reflectance threshold to a biometric identification process.Examples will be described with reference to the system 100 as shown inFIG. 1. The reference to the system 100 is not intended to limitpractices in accordance with this disclosure to the system 100. Process300 operations can include receiving 302 the captured image, e.g., fromthe system 100. Referring to FIG. 1, image capturing can include thelight source 102 illuminating, directly or via the light diffuser 112,the subject's face 110 and other surfaces of the subject 108, thebackground surface 106 if used, and the digital camera 104 capturing thereflected light, as a captured image. Process 300 can then proceed toquantifying 304 the captured image's relative reflectance. Operations inquantifying 304 can include separating facial pixels from other pixelsof the captured image. Operations in quantifying 304 can also includecomputing facial pixels' respective luminances, and normalizing thecomputed respective luminances using, for example, a mean of thebackground luminance. Specific implementations and operations in thequantifying 304 are described in greater detail in later sections ofthis disclosure.

The process 300 can proceed from quantifying 304 the relativereflectance of the captured image to applying a reflectance thresholdqualification 306. In various embodiments, the reflectance thresholdqualification 306 determines, at least in part, whether the capturedimage is suitable for use in biometric identification. The reflectancethreshold qualification 306 can include comparing, to one or morethresholds, the relative reflectance value output from the quantifying304. The one or more thresholds can include, for example, a ceilingthreshold, i.e., maximum allowable reflectance, or can include a floorthreshold, i.e., a minimum allowable reflectance, or can include both.The reflectance threshold qualification 306 can generate, andcommunicate for subsequent actions or processing, a reflectancequalification indicator of whether the relative reflectance from thequantifying 304 meets the threshold.

The process 300 can proceed, as shown by the “Yes” “outbranch from flowlogic block 308, to biometric identification 310 when the reflectancethreshold qualification 306 indicates the relative reflectance meets,i.e., is not outside, the reflectance threshold. In an embodiment, asshown by the dotted line from the “No” outbranch of flow logic block308, the process 300 can proceed to action 312 when the reflectancethreshold qualification 306 indicates the relative reflectance does notmeet, i.e., is outside, the reflectance threshold. Operations in theactions 312 can be application-specific. In one or more embodiments,operations in the actions 312 can include, without limitation,post-processing correction of the captured image, directed to obtaininga relative reflectance that meets the reflectance thresholdqualification 306. In one or more embodiments, operations in the actions312 can include selecting a remediation, or selecting among a set ofremediations, as described in greater detail in later sections. Theprocess 300 can include, in an embodiment, a determination 314 ofwhether to forward the captured image to the biometric identification310 regardless of the reflectance threshold qualification 306 indicatingthe relative reflectance is outside the threshold. Logic configurationof the determination 314, including factors the determination 314considers can be application-specific.

Referring to the FIG. 3 quantifying 304 of the relative reflectance ofthe captured image, example configuration in accordance with one or moreembodiments will now be described. Description will reference FIG. 4which is part of this disclosure and shows a logic flow diagram ofoperations of a process 400. An instance of the process 400 can includereceiving 402 a captured image of a subject, for example, receiving fromthe FIG. 3 capturing 302 a captured image of the FIG. 1 subject 106. Thereceiving 402 can be at a particularly configured processing resource,such as described later in reference to FIG. 16. FIG. 5 is a graphic 500of certain patterns of luminance that can be carried in the capturedimage received in 402. As shown the luminance patterns can definelighter regions, such as the examples labeled “LHT,” and darker regions,such as the examples labeled “DK.” As described in greater detail insubsequent paragraphs, operations in the process 400 can includedetecting the facial region by detecting face-indicating signaturepatterns of LHT and DK. Operations in the process 400 can also includediscarding DK region pixels from consideration in determining relativereflectance of the captured image, as also described later in greaterdetail.

Upon receiving 402 the captured image the process 400 can proceed toobtaining 404, from the captured image, facial pixels 406 and backgroundpixels 408. Operations in obtaining 404 the facial pixels 406 andbackground pixels 408 can include applying a face detecting 410 to thecaptured image, followed by dividing 412 the image into the facialpixels 406 and remainder pixels 414. The dividing 412 can be based atleast in part on facial region position information from the facedetecting 410.

Regarding the face detecting 410, as introduced above implementationscan employ detecting human faces' signature patterns of LHT and DK. Onesuch pattern can be a characteristic LHT, DK, LHT pattern formed byhuman eyes spaced on opposite sides of a human nose bridge. An example“three-rectangle” feature implementation of the face detecting 410 willnow be described in reference to FIGS. 6A and 6B.

Referring to FIG. 6A, operations in the three-rectangle featureimplementation of the face detecting 410 can include iterativelyapplying, e.g., in a stepping manner, three-rectangle features to thecaptured image, as shown by the three instances, 604A, 604B, and 604C,within the rectangular region 602. For purposes of description, thethree instances, 604A, 604B, and 604C, will be collectively referencedas “three-rectangle features 604.” Shown in FIG. 6B rectangular area602′ are annotated versions, items 604A′, 604B′, and 604C′, of the FIG.6A three-rectangle features 602. The annotation appears as a shading ofthe outer two rectangles of 604A′, 604B′, and 604C′. The shadingrepresents operations of subtracting the sum of the intensity of pixelsinside one or more rectangles in each three-rectangle feature 604 fromthe intensity of pixels within the remaining one or more rectangles. Inthis way, eyes, a nose, and a mouth can be detected. The three-rectanglefeature 602 implementation of the face detecting 410 is only an example.Alternative implementations of the face detecting 410 can applytechniques using, for example and without limitation, two-rectanglefeatures, four-rectangle features, and combinations of any two or moremultiple rectangle features.

Referring to FIG. 4 and FIG. 7, operations in dividing 412 the capturedimage into facial pixels 406 and remainder pixels 414 include creating702 a boundary aligned with and surrounding a region of the capturedimage indicated by the face detecting 410. After creating 702, theboundary operations can include dividing 704 pixels of the capturedimage into the facial pixels 406 and the remainder pixels 414. Thedividing 704 can use the boundary as a demarcation. In animplementation, FIG. 4 remainder pixels 414 such as obtained from theFIG. 7 dividing 704 can be used as the background pixels 408. Also, inan implementation, the FIG. 4 background pixels 408 can be obtained froma sampling 416 of remainder pixels 414, as obtained from the FIG. 7dividing 704, as described in greater detail in later paragraphs.

FIG. 8A shows aspects of creating and applying a mask 802 as an exampleof the above-described FIG. 7 creating 702 a boundary around and alignedwith the detected facial region. The mask 802 can be a circular mask, asshown in FIG. 8A. In a modification, the mask 802 can be formed with analternative geometry, e.g., an ellipse or oval. FIG. 8B shows a zoom-outfrom the FIG. 8A view, also showing an example background region 808.

Referring to FIG. 4, process 400 can proceed from obtaining 404 facialpixels 406 and background pixels 408 from the captured image, toselecting 418 facial skin pixels 420 from the facial pixels 406.

An implementation of the selecting 418 can include operations as shownin the FIG. 9 process 900. The process 900 can include calculating 902luminance values of the facial pixels 406, then discarding 904 outlierfacial pixels. Luminance values of the facial pixels 406 can becalculated, for example, based on a weighted sum of associated colorcomponent values, e.g., luminance value calculation. Outlier facialpixels discarded at 904 can be facial pixels 406 with a luminance abovea predefined upper level, such as, without limitation, 1.5 standarddeviations above a mean of the set of luminance values. Facial pixels406 with luminance values exceeding this predefined upper level mayrepresent, for example, features other than skin, such as irises ofeyes, teeth, and eyewear, for example. Another example of outliers fordiscarding 904 can be a predefined lower level, such as but not limitedto, 1.5 standard deviations below the mean of the set of luminancevalues. Facial pixels 406 with luminance values below this predefinedlower level may represent features other than skin, such as dark facialhair, pupils, nostrils, and oral cavities, for example.

Accordingly, after discarding 904 outlier facial pixels from the facialpixels 406, the remainder can be facial skin pixels 420 that are withinan upper and lower standard deviation levels for luminance values.Similar approaches can be used for other phenotypes or covariates withthe applicable standard deviation being set based on the appliedphenotypic property implemented in the method.

Graphic representation of the FIG. 4 selecting 418 and FIG. 9 process900 discarding 904 can be seen in FIG. 10, where graphic 1002 shows anoriginal pixel resolution of all the facial pixels 406, graphic 1004shows a coarse representation of the facial pixels in 1002, and graphic1006 shows a result of the discarding, e.g., the discarding 904 ofpixels with luminance value below a predefined lower level.

The process 400 can then proceed to normalizing 422 the luminance of thefacial skin pixels 420. The normalizing 422 the luminance of the facialskin pixels 420 produces a normalized luminance value 424 of the facialskin pixels. In an aspect, the normalizing 422 can utilize, as thenormalizing reference, a mean 426 of the background pixels 408.Operations in the process 400 can therefore include computing 428 themean 426 of the background pixels 408 for input to the normalizing 422,as shown in FIG. 4. For purposes of subsequent description, the mean 426of the background pixels 408 will be alternatively referred to as a“first mean.” As shown in FIG. 11, calculation of the first mean caninclude obtaining 1102 background pixels (FIG. 4, 410) from remainderpixels and calculating 1104 the mean. FIG. 12 shows a removal of thesubject, leaving only background pixels 1202, and showing includes theexample background region 808 identified above in reference to FIG. 8B.Area 1204 graphically depicts a mean of the background pixels, whichappears as a mid-level grey.

Operations of the process 400 can proceed from the normalizing 422 theluminance values of the facial skin pixels 420 to calculating 430 therelative skin reflectance value 432, based on the normalized luminancevalue 424 of the facial skin pixels 420. In an implementation, thecalculating 430 the relative skin reflectance value 432 can generate therelative skin reflectance value 432 as or based on a mean of thenormalized luminance value 424 of the facial skin pixels 420. Forpurposes of subsequent description, the mean of the normalized luminancevalue 424 of the facial skin pixels 420 (generated within the FIG. 4normalizing 422) will be alternatively referred to as a “second mean.”

In the selecting 418 of facial skin pixels 420, operations can includecalculating luminance of all the facial pixels 406. An adaptation can bea calculating a luminance of only a portion of the facial pixels 406.The portion, e.g., the number of the facial pixels 406 used for thecalculating in 418 of luminances can vary based on a variety of factors.Examples of the factors can include, but are not limited to, systemrequirements, e.g., processing resources; operational requirements,e.g., throughput; and design preference. In embodiments substantiallyall the pixels are used, while in others a computing system isconfigured to sample pixels. Implementation of selecting, for using onlya portion of the facial pixels, can be based on a variety of factors,including location (e.g., selected from a portion associated with acheek), representative nature, their similarity/difference in comparisonto other pixels and the like techniques. For example, a sampling ofpixels can be used to promote computational efficiency and speed, whilein other implementations a comparatively large number of pixels can beused to promote accuracy.

In an aspect, bounding can be used to eliminate extraneous portion ofthe face and/or adjacent or directly adjacent “non-face” pixels that arenot representative of the overall or applicable skin reflectance for theface. For example, pixels associated with hair or boundary portion ofthe face can be eliminated because they fall outside the bounding and donot represent the overall reflectance of the of skin within the face.Bounding may be used to avoid processor use (e.g., calculation ofluminescence values) that would otherwise be performed on pixels (e.g.,data) that are not representative of, or tend to skew skin reflectancecalculation. Systems, devices, and methods that implement otherphenotypic measures can likewise benefit from use of this technique toeliminate data that is of lesser relevance than that of other data thatprovides a more accurate assessment of the in-question phenotypiccharacteristic.

In contemplated applications, faces may show various ambiguities indemarcations and boundaries between their facial pixels and backgroundpixels, and often showing certain non-uniformities of facial skinpigmentation, a selecting 418 can be applied to facial pixels 406, toobtain facial skin pixels better representative of facial skin.

The facial portion of the image can be made up of data points (e.g.,pixels) associated with values for color components, i.e., colorcomponent values that can be represented in a variety of ways, such asred, green, blue (RGB) or cyan, magenta, yellow, and black, or the likeapproaches for categorizing pixel color.

For example, the use of specular reflectance data for facial skinimplements a sampling technique that results in the selection of pixelsthat are more representative of the phenomena than other facial pixelsthat are not.

In embodiments, devices, systems, method, steps, and approachesconsistent with this disclosure are configured to account for factorsimpacting phenotypic characteristics, including but not limited to pixelintensity. Example factors include physical properties of the skin andunderlying tissue (layers, absorbers, and scattering coefficients),physical properties of the skin surface (specular reflectance), andimaging artifacts (incident light intensity, camera gain). For example,systems and method are implemented to remove at least some imagingartifacts through post-acquisition image manipulation or by changing theconditions under which a subsequent image is captured, e.g., using alight source or a different light source and/or acquisition device,changing image capture device parameters, or the like techniques forresulting in an image with facial skin reflectance that is suitable foruse, e.g., within range. Thus, a computing system can be programmed toeliminate or minimize confounding imaging artifacts effects relative toan image in which this is not done.

Optionally, non-facial pixels from a captured image, such as backgroundpixels, can be used as a basis for correcting facial luminescencevalues. In examples, a sample of a background portion of an in-questionimage is obtained. For example, a portion of the pixels forming abackground (e.g., a neutral portion of the image such as a gray wallbehind the person in the image) is obtained and are processed tocalculate a background pixel intensity, e.g., mean of the associatedbackground intensities.

In an embodiment, features can include, but are not limited to,quantification of relative reflectance in captured images, reflectancethreshold qualification for use in biometric identification, incombination with various adaptive, selective remediations of reflectanceoutside of threshold. Remediations can include, without limitation,post-processing image reflectance correction, and remediation of imagecapture processes.

FIG. 13 shows a flow diagram of operations in a process forquantification of relative reflectance in captured images, reflectancethreshold qualified biometric identification, and adaptive, selectiveremediations of reflectance outside of threshold. Examples will bedescribed with reference to the system 100 shown in FIG. 1. Thereference to the system 100 is not intended to limit practices inaccordance with this disclosure to the system 100.

In an instance, operations in the process 1300 can include imagecapturing 1302. Referring to FIG. 13, image capturing 1302 can includethe light source 102 illuminating, directly or via the light diffuser112, the subject's face 110 and other surfaces of the subject 108, thebackground surface 106 if used, and the digital camera 104 capturing, asa captured image, the illuminated surfaces. From image capturing 1302,operations in the process 1300 can proceed to quantifying 1304 thecaptured image's relative reflectance. The quantifying 1304 can apply,but is not limited to, the FIG. 4 process 400 and implementationsthereof, as described above in reference to FIGS. 5 through 12.

The process 1300 can proceed from quantifying 1304 the relativereflectance to reflectance threshold qualification 1306. As describedabove, for example, in reference to FIG. 3 reflectance thresholdqualification 306, operations in reflectance threshold qualification1306 can include comparing, to one or more thresholds, the relativereflectance value output from the quantifying 1304. The one or morethresholds can include, as described above, a ceiling threshold, or afloor threshold, or both. The reflectance threshold qualification 1306can generate a reflectance qualification indicator, which can indicatewhether the relative reflectance output from the quantifying 1304 meetsthe qualification threshold(s).

In accordance with one or more embodiments, operations in the process1300 following reflectance threshold qualification 1306 can includeautomatic selecting 1308, as a selected next process, between abiometric identification 1310 using the received image and a remediationprocess 1312. The automatic selecting 1308 can be based at least in parton the indication, e.g., by reflectance qualification indicator, ofwhether the captured image is a suitable reflectance captured image or anot suitable reflectance captured image.

In the FIG. 13 implementation, the automatic selecting includes a binaryselecting 1314 and a remediation selecting 1316. The binary selecting1314 directs the process 1300, in response to the reflectance thresholdqualification 1306 indicating a suitable reflectance, to the biometricidentification 1310. The directing of the flow by the binary selecting1314 is shown in FIG. 13 as via the block 1314 “Yes” outbranch. Thebinary selecting 1314 directs the flow 1300, in response to thereflectance threshold qualification 1306 indicating a suitablereflectance, to the remediation selecting 1316, shown in FIG. 13 as viathe block 1314 “No” outbranch.

It will be understood that the remediation selecting 1316 can be omittedand, instead, one or more embodiments in accordance with this disclosurecan provide only a fixed, single remediation option, e.g., repeat theimage capture.

The FIG. 13 implementation of the remediation selecting 1316 providesselection among, in an example four different remediation processes,represented in the figure as the following four remediation paths: afirst remediation process path, abbreviated on the figure as “1^(st)RMD”, a second remediation process path, abbreviated as “2^(nd) RMD,” athird remediation process path, abbreviated as “3^(rd) RMD,” and afourth remediation process path, abbreviated on the figure as “4^(th)RMD.” It will be understood that this is only one example. Onealternative implementation can provide selection among fewer than fourremediation processes. Another example alternative, as described above,can provide a fixed, single remediation.

In the FIG. 13 example, the first remediation path includes an adjustcapture parameters and retaking 1318, which can adjust the captureparameters and retaking the image, e.g., by returning to the imagecapturing 1302. As visible in FIG. 13, information input to the captureadjusting and retaking 1318 can include, in addition to the capturedimage, an image ID, reflectance failure data, and image captureparameters. The image ID can be, for example a temporary identifierassigned by the kiosk of FIG. 1. The image ID can include an identifierof the subject. The threshold failure data can include, for example, anidentifier of which reflectance threshold was exceeded, e.g., the floorthreshold, or the ceiling threshold. The threshold failure data can alsoinclude, for example, a quantification, e.g., “the reflectance wasgreater than 1.5 times the ceiling threshold,” or “the reflectance wasless than 0.8 times the floor threshold.” It will be understood that“1.5” and “0.8” are arbitrary examples, not intended as any limitation.The image capture parameters can define one or more parameters used inthe capture of the image that was determined by the reflectancequalification 1306 as being non-conforming. Specific examples caninclude, but are not necessarily limited to, one or more parameters ofthe lighting, one or more camera gain parameters, or one or moreparameters of the light diffusion, or any combination or sub-combinationthereof.

In an embodiment, the capture adjusting and retaking 1318 can beconfigured to use the image ID, the threshold failure data, and theimage capture parameters to determine an adjustment of the image captureparameters for retaking the subject's image. In an aspect, theremediation selecting 1316, or the capture adjusting and retaking 1318,or both, can be configured to determine when no further adjustment, orat least no further adjustment having reasonable likelihood ofsuccessful result, is practical. In one example of such configuration,the determination can invoke an intervention 1324, shown in FIG. 13 as a4^(th) remediation. Configuration for determining no further adjustmentof capture parameters is practical can include, for example, storage ofa record of iterations of the capture adjusting and retaking 1318.

In the FIG. 13 example, the second remediation path includes postcapture reflectance correction 1320A, followed by post processdetermining 1320B of whether the post capture reflectance correction1320A was successful. Implementations of post capture reflectancecorrection are described in greater detail in later sections of thisdisclosure. Implementation of post process determining 1320B whether thepost capture reflectance correction 1320A was successful can includeincorporating the post process determining 1320B in the post capturereflectance correction 1320A or can be implemented as a re-routing tothe quantifying 1304.

As visible in FIG. 13, the process 1300 can proceed from a “Yes” resultof the post process determining 1320B to the biometric identification1310. As also visible, in response to a “No” result of the post processdetermining 1320B, the process 1300 can return to the remediationselection 1316. Operations subsequent to such a return to theremediation selection 1316 can include the 4^(th) remediation,identified above in this example as invoking an intervention 1324, e.g.,by security personnel.

In the FIG. 13 example, the third remediation path includes an automaticforwarding 1322 to the biometric identification 1310, e.g., a fallbackselecting of biometric identification, irrespective of being determinedas having a non-suitable reflectance.

As stated above, the FIG. 13 four-option configuration of remediationselecting 1316 is only one example. One alternative configuration mayinclude only one remediation. A schematic of such configuration can beconstructed by omitting from the present FIG. 3 all but one of the fourremediation paths and replacing remediation selecting 1316 with a directconnection of the “No” output of the binary selecting 1314 to that oneremediation path. One example of such construction can be according tothe following modification of FIG. 13: omit blocks 1316, 1318, 1320A,1320B, and 1322 and directly connect the “No” out path from block 1314to the input of intervention 1324. Another remediation selectingconfiguration can be a three-option configuration, e.g., by omitting theadjust capture parameters and retaking 1318, or by omitting post capturereflectance correction 1320A. Still another remediation selectingconfiguration can be a two-option configuration, implemented, e.g., byomitting any two of the four remediation paths described above, andadapting the remediation selecting 1316 accordingly.

Another remediation selecting configuration can include more than fourremediation paths. One example can include configuring the biometricidentification 1310 with a plurality, for example integer Q, differentbiometric matching algorithms, and configuring the remediation selecting1316 to include a process for determining, based for example on therelative reflectance output from the quantifying 1304, whether one orthe Q different biometric matching algorithms may be better suited to acaptured image that, according to the current configuration of thereflectance threshold qualification 1306, is unsuitable, at least forthe presently selected biometric matching algorithm. In an aspect, theprocess for determining whether one or the Q different biometricmatching algorithms may be better suited can be configured to receivethe above-described threshold failure data from the reflectancethreshold qualification 1306.

It will be understood that graphical arrangement of FIG. 13 blocks isnot necessarily indicative of allocation of hardware segmentation

In one or more embodiments, computing and database resources forperforming operations in one or more of the different blocks of theprocess 1300 can be separate and independent from computing resourcesfor operations in other of the different blocks of the process 1300.Examples can include, but are not limited to, biometric identification1310 being performed on a computing and database resources owned by afirst entity, and other operations, such as post-processing reflectancecorrection 1320A and determining 1320B of whether the post-processingreflectance correction 1320A was successful, being performed oncomputing and database resources owned by a second entity. Anotherexample, not necessarily exclusive of the first example, can includeoperations in the quantifying 1304 of reflectance being performed oncomputing and database resources owned by one entity, and operations inthe capture adjusting and retaking 1318 being performed on computing anddatabase resources owned by another entity.

Bounding can be used to eliminate extraneous portion of the face and/oradjacent or directly adjacent “non-face” pixels that are notrepresentative of the overall or applicable skin reflectance for theface. For example, pixels associated with hair or boundary portion ofthe face can be eliminated because they fall outside the bounding and donot represent the overall reflectance of the of skin within the face.Bounding may be used to avoid processor use (e.g., calculation ofluminescence values) that would otherwise be performed on pixels (e.g.,data) that are not representative of, or tend to skew skin reflectancecalculation. Systems, devices, and methods that implement otherphenotypic measures can likewise benefit from use of this technique toeliminate data that is of lesser relevance than that of other data thatprovides a more accurate assessment of the in-question phenotypiccharacteristic.

In contemplated applications, faces may show various ambiguities indemarcations and boundaries between their facial pixels and backgroundpixels, and often showing certain non-uniformities of facial skinpigmentation, a selecting 418 can be applied to facial pixels 406, toobtain facial skin pixels better representative of facial skin.

In examples, luminance values of the facial pixels are calculated from aweighted sum of associated color component values, e.g., luminance valuecalculation.

Facial pixels with a luminance value above a predefined upper level orbelow a predefined lower level can be considered as outliers that arenot used. An example of a predefined upper level is 1.5 standarddeviations above a mean of the set of luminance values. Facial pixelswith luminance values exceeding this predefined upper level mayrepresent features other than skin, such as irises of eyes, teeth, andeyewear, for example. An example of a predefined lower level is 1.5standard deviations below the mean of the set of luminance values.Facial pixels with luminance values below this predefined lower levelrepresent features other than skin, such as dark facial hair, pupils,nostrils, and oral cavities, for example. The outlier facial pixels canbe discarded from the facial pixels, leaving facial skin pixels. Inexamples, the remaining facial skin pixels are those facial pixels thatare within an upper and lower standard deviation levels for luminancevalues. Similar approaches can be used for other phenotypes orcovariates with the applicable standard deviation being set based on theapplied phenotypic property implemented in the method.

The facial portion of the image can be made up of data points (e.g.,pixels) associated with values for color components, i.e., colorcomponent values that can be represented in a variety of ways, such asred, green, blue (RGB) or cyan, magenta, yellow, and black, or the likeapproaches for categorizing pixel color.

For example, the use of specular reflectance data for facial skinimplements a sampling technique that results in the selection of pixelsthat are more representative of the phenomena than other facial pixelsthat are not.

In embodiments, devices, systems, method, steps, and approachesconsistent with this disclosure are configured to account for factorsimpacting phenotypic characteristics, including but not limited to pixelintensity. Example factors include physical properties of the skin andunderlying tissue (layers, absorbers, and scattering coefficients),physical properties of the skin surface (specular reflectance), andimaging artifacts (incident light intensity, camera gain). For example,systems and method are implemented to remove at least some imagingartifacts through post-acquisition image manipulation or by changing theconditions under which a subsequent image is captured, e.g., using alight source or a different light source and/or acquisition device,changing image capture device parameters, or the like techniques forresulting in an image with facial skin reflectance that is suitable foruse, e.g., within range. Thus, a computing system can be programmed toeliminate or minimize confounding imaging artifacts effects relative toan image in which this is not done.

Optionally, non-facial pixels from a captured image, such as backgroundpixels, can be used as a basis for correcting facial luminescencevalues. In examples, a sample of a background portion of an in-questionimage is obtained. For example, a portion of the pixels forming abackground (e.g., a neutral portion of the image such as a gray wallbehind the person in the image) is obtained and are processed tocalculate a background pixel intensity, e.g., mean of the associatedbackground intensities.

FIG. 14 shows a flow diagram of operations in a process 1400 ofbiometric identification and access control, with image relativereflectance thresholding according to one or more embodiments.Description assumes an electronically actuated access control device1401, e.g., e-gate. The electronically actuated access control device1401 can be, for example, a “man trap.” Description assumes as input acaptured image and a relative skin reflectance (RSR) of the capturedimage. The captured image can be received, for example, from the digitalcamera 104 of the FIG. 1 system 100. The RSR can be received, forexample, from an implementation of the FIG. 3 quantifying 304 ofrelative reflectance.

Operations in process 1400 can include threshold RSR qualification 1402,which can apply RSR against, for example, a ceiling threshold T(C) and afloor threshold T(F). Threshold RSR qualification 1402 can indicatesuitability 1404A of the captured image if RSR is within the suitablerange, e.g., meets T(C) and T(F), and can indicate non-suitability 1404Bof the captured image if RSR value is not within the suitable range,e.g., does not meet one of T(C) and T(F). The T(C) and T(F) values maybe pre-determined. In embodiments T(C) and T(F) may be updated,dynamically or a periodically, for example, based on current selectionof biometric algorithms, or on a dynamic updating to adjust a likelihoodthat facial recognition will lead to an inconclusive result.

In response to the threshold RSR qualification 1402 indicatingsuitability 1404A of the captured image, the process 1400 proceeds tobiometric identifying 1406. Based at least in part on a result of thebiometric identifying 1406 the process 1400 can then instruct 1408 theelectronically actuated access control device 1401 to perform an accesscontrol action. The electronically actuated access control device 1401can be, for example, a gate or a turnstile, and the instruction 1408 caninstruct the device 1401 to open, close, stay open, stay closed, or thelike.

In response to the threshold RSR qualification 1402 indicatingnon-suitability 1404B of the captured image, the process 1400 canproceed to flagging 1410 the current captured image for a follow onaction, for example, a selection 1411 between image capture remediation1412 and applying a post processing correction 1414 to the capturedimage. The post processing correction 1414 can include image processingconfigured to generate, from the captured image, a corrected reflectanceimage, having an RSR suitable for biometric identifying 1406. Theprocess 1400 can include a determining 1416 of whether the postprocessing correction 1414 is successful. The process 1400 can include,for instances where the determining 1416 is a negative, a routing toeither an action 1418 or the image capture remediation 1412. Selectionlogic for selecting between the action 1418 and the image captureremediation 1412 can be provided. The process 1400 can include with theimage capture remediation 1412 a generation of updated or adjustiveimage capture parameters, and a retaking 1420 of the image of thesubject to obtain a second captured image. The process 1400 can alsoinclude, for the second captured image a determining 1422 of therelative reflectance of the second captured, followed by return to thethreshold RSR qualification 1402.

In the FIG. 14 configuration, biometric identifying 1406 can includeobtaining results 1424 of biometric comparison (BC) between the capturedimage and reference image(s). The biometric comparison can be configuredas a one-to-one comparison between the captured image of a subject and asingle reference image of the subject (also referred to as 1:1matching). Regarding the reference image, in one or more embodiments,the reference image can be retrieved from an identification credentialsuch as a driver's license. In another embodiment, the reference imagecan be retrieved from an electronic credential such as a mobile driver'slicense (mDL). In another embodiment the electronic credential can beprovisioned to a mobile device such as a smartphone or the like. It willbe understood that the above-identified examples are not exhaustive andare not mutually exclusive. For example, one or more embodiments canretrieve the credential, or multiple credentials of a subject, from adriver's license, an mDL, or other sources. In embodiments, metadatarelated to the reference image in such a credential can be communicatedas well to serve as a basis for informing the system performing theidentification of conditions associated with acquisition of thereference image.

Operations in obtaining 1424 results of biometric comparison between thecaptured image and reference image(s) can include a one-to-many (1:Nmatching) comparison. The 1:N comparison can be, for example, betweenthe captured image and reference images retrieved from an image gallery.In such implementation, operations can include flagging 1410 whether thecaptured image matches any of the reference images gallery to asufficient standard, e.g., a matching threshold. Operations associatedwith the 1:N matching can also include determining a match, when 1:Nmatching is performed between the captured image and an image gallery.The results of the biometric comparisons are obtained (biometricmatching).

When the result or results of the biometric comparison exceeds amatching threshold TH, the process 1400 may deem a match was made and,as indicated by the “Yes” output of branch 1426, can proceed to aselecting 1428. In an example of 1:N matching, selecting 1428 can be thehighest-scoring biometric match, and the process 1400 can proceed to1430, identify the subject as the individual associated with the galleryimage having the highest biometric matching result, and then tooutputting 1432 an identification message.

Referring to the comparison at 1424, in implementations using 1:1matching, when the biometric comparison result exceeds the matchingthreshold TH, the subject is identified as the individual associatedwith the asserted identity and process 1400 can proceed directly tooutputting 1432 the identity indication message indicating the identityof the subject.

In an embodiment, the process 1400 can include generating 1434, based atleast in part on a result of the biometric identification 1406, aninstruction to the electronically actuated access control device 1401,e.g., an access control message, instructing the device 1401 to eitheropen, or stay open, or to close or stay closed. The instruction can begenerated, for example, as an access control signal, having a value setbetween an access open value and an access closed value.

One or more embodiments can include image capture remediation that caninclude but is not limited to calculating adjustments to the imagecapture process to re-take the image, i.e., obtain a second capturedimage of the subject, having a likelihood of having a suitablereflectance. Further features can include, for example by machinelearning, general adjustments to the image capturing process that, forall subjects or for certain ages, genders and so forth of subjects, arelikely to obtain a higher percentage of captured images showing suitablereflectance.

FIG. 15 illustrates a flow diagram of operations in a process 1500 ofskin reflectance correction in biometric image capture in accordancewith one or more embodiments. Operations in the process 1500 can includereceiving 1502 a first captured image of a subject, from an imagecapturing resource 1504. In an embodiment image capturing resource 1504can be configured according to the FIG. 16 system 1600. Referring toFIG. 16, an implementation of the system 1600 can include a digitalcamera 1602 and one or more light sources such as the example firstlight source 1604-1 and second light source 1604-2 (hereinaftercollectively “light sources 1604”). The light sources 1604 can be atrespective positions relative to a position DL where a subject 1606 maystand or sit for image capture. In an image capture, the light sources1604 may illuminate skin surfaces of the subject's face 1608 and othersurfaces, portions of the light are reflected back as reflection rays1610, which are captured by the digital camera 1602 to form a capturedimage. It will be understood that the FIG. 16 population of two lightsources 1604 is neither a limitation nor an indication of preference.Implementations of system 1600 can include more than two light sources1604 and can include a single light source 1604. In implementations witha plurality of light sources 1604, one or more of the light sources 1604can be of one type, and one or more of the light sources 1604 can beamong one or more other types. The light sources 1604 can be continuouslight sources or can be flash sources or can be a mixture of continuousand flash.

In various embodiments, the system 1600 can include an image captureparameter storage 1612, configured to store one or more image captureparameter values, generated by processes such as process 1500. Examplesshown in the FIG. 16 implementation, collectively referenced forpurposes of description as “image capture parameter values 1614,”include camera gain 1614-1; camera height 1614-2; camera spectralsensitivity (abbreviated “STY-CMD” in the FIG. 1614-3; lightingintensity 1614-4, light diffusivity 1614-5, lighting color-tint 1614-6,light source arrangement (abbreviated “Light Source AGM” in the figure)1614-7, and background configuration (abbreviated “CFG” in the figure)1614-8. It will be understood that the FIG. 16 population andconfiguration of image capture parameter values 1614 is only an example.Embodiments can omit one or more of the specific examples shown in FIG.16. Embodiments can include a larger population of image captureparameter values 1614 than included in the FIG. 16 example values of theimage capture parameter values 1614. In an aspect, one or more of theexample image capture parameter values 1614 shown in FIG. 16 can beseparated into a vector-like, multi-valued parameter that can provide,for example, a finer granularity to adjustments to the image captureprocess.

It will also be understood that the image capture parameter storage 1612is a logic resource and not necessarily implemented as a separate,discrete hardware. For example, portions of image capture parameterstorage 1612 can be provided by local storage resources of the system1600 components, e.g., parameter storage feature of the digital camera1602, light emitting diode (LED) palette command storage of LEDimplementation of one or more of the light sources 1604.

In an aspect, the system 1600 can include a logic interface of the imagecapture parameter storage 1612 with resources supporting processesaccording to various embodiments for calculating reflectance correctingimage capture parameters, e.g., the FIG. 15 process 1500 and otherprocesses described in greater detail in later sections of thisdisclosure. FIG. 16 shows, as one example of such interface, a genericlogic network 1616 and a logic network interface 1618. The generic logicnetwork 1616 and logic network interface 1618 will be understood to be alogic coupling, having no limitation as to hardware. The generic logicnetwork 1616 and logic network interface 1618 can encompass, forexample, communication between operations of image capture, e.g., andoperations of reflectance correcting image capture parameter calculationcan be local to, and even integrated or otherwise shared at least inpart with, hardware of system 1600.

The system 1600 can include a height adjustable camera support 1620 forthe digital camera 1602. The height adjustable camera support 1620 canprovide, for example, via a reversible actuator gear 1620A movementalong a height axis HD, to adjust a height J1 of the digital camera1602. The height J1 may be controlled by the camera height 1614-2 amongthe reflectance correcting image capture parameter values 1614. Theheight J1 can be relative to a floor surface FS that can be, forexample, a reference for height J2 of the face 1608 of the subject 1606.The system 1600 can also provide the digital camera 1602 with the cameragain 1614-1 and camera spectral sensitivity 1614-3. It will beunderstood that “provide,” in the context of providing image captureparameters to components and functionalities of the system 1600, caninclude translating the parameter values to a format or protocolappropriate for the components and functionalities.

The FIG. 16 population of two light sources 1604 is neither a limitationnor an indication of preference. Implementations of system 1600 caninclude more than two light sources 1604 and can include a single lightsource 1604. In implementations with two or more light sources 1604, oneor more of the light sources 1604 can be of one type, and one or more ofthe light sources 1604 can be of another, or from among a plurality ofother types.

In an implementation, one or more of the light sources 1604 can includea pivotable support, such as the example pivotable light support 1622supporting the second light source 1604-16. The pivotable lightsupport(s) 1622 can be controlled, for example, by the light sourcearrangement parameter value 1614-6, or by an additional image captureparameter value 1614. The pivotable light support 1622 is shown, forpurposes of example, as pivotable about a first pivot axis AX1 and abouta second pivot axis AX2. Control of one or more of the light sources1604, particularly ones such as the second light source 1604 that are ona pivotable light support, can include a focusing reflector 1604-2A.

One or more of the light sources 1604 can include light intensitycontrollability that can be set, for example, by the lighting intensity1614-4 parameter.

The system 1600 can include a light diffuser 1624, controllable forexample by the light diffusivity 1614-5 image capture parameter, betweenat least one of the light sources 1604 and the subject 1604. The lightdiffuser 1624, if used, may be implemented by an adjustable lightdiffusion apparatus, e.g., a commercial off-the-shelf (COTS) adjustablediffuser such as available from various vendors. The FIG. 16configuration of the light diffuser 1624 is only an example. One examplealternative can include, but is not limited to, an incorporation of thelight diffuser 1624 or equivalent into, for example, a projection lensof the first light source 1604-1. Another alternative can include, butis not limited to, incorporating a first instance of light diffuser 1624or equivalent into a projection lens of one among the light sources 1604and positioning another, non-incorporated light diffuser between thesubject 1606 and another of the light sources 1604.

One or more of the light sources 1604 can be implemented as an LED coloradjustable light, either continuous or flash. Color adjustment can becontrolled, for example, by the lighting color-tint 1614-5.

In one or more embodiments, the light source arrangement parameter1614-6 can be configured to incorporate, for example, one or more of theother image capture parameter values 1614, for example, one or both ofthe light intensity 1614-4 and the light diffusivity 1614-5. In oneexample implementation the light source arrangement parameter 1614-6 canbe configured as a selector, for selecting among, for example, up tointeger LQ different light source arrangements. One adaptation includeswith the light source arrangement parameter 1614-6 one or more lightingcomponent specific parameters, e.g., a pointing direction for thepivotable light support 1622.

Corresponding to and controlled by the background configuration 1614-7,the system 1600 can include, in an embodiment, a background surface1626.

Implementations of the system 1600 can also include, for example, adisplay 1628 to present the subject 1606 with prompts, suggesting to thesubject 1606 an adjustment of stance or posture. In the example visiblein FIG. 16, the prompt is a suggestion for rotating or tilting of thesubject's face 1608, to an orientation that is deemed likely to provide,from an image capture, a captured image with a suitable reflectance.

The light sources 1604 are not necessarily a system 1600 dedicatedresource. For example, system 1600 can utilize, or can be switchablyconfigured to utilize, ambient light as one or more of the light sources1604.

In an embodiment, system 1600 can include an illumination source orplurality of information sources that are outside the visible lightspectrum, e.g., ultraviolet (UV) light. The feature can be included as asupplement or as an alternative to visible light. In another adaptation,the system 1600 can use, instead of or in addition to the digital camera1602, an image capture device other than a camera.

Referring to FIG. 15, and continuing with description of the process1500, upon receiving 1502 from the image capture resource 1504 the firstcaptured image of the subject (e.g., subject 1606 shown in system 1600)the process 1500 can proceed to identifying 1506 whether the capturedimage's relative reflectance is outside of a reflectance threshold. Theidentifying 1506 can be implemented as quantifying 1507A of the relativeskin reflectance (RSR) of facial skin regions of the captured image,followed by comparing 1507B the RSR to the threshold. Based at least inpart on the result of the comparing 1507B being “Yes,” a determinationat 1508 is “No,” the relative reflectance is not outside of thethreshold, and the process 1500 proceeds to biometric identification1510. The biometric identification 1510 and other operations in theprocess 1500 can be performed, for example, on shared computationalresources or can be performed on separate computational resources, asindicated by the dotted line graphics representing biometricidentification 1510.

Regarding the reflectance threshold applied by the comparing 1507B,implementations can include, as described above, a floor threshold, or aceiling threshold, or can include both.

Referring again to the comparing 1507B, based at least in part on theresult being “No,” the determination at 1508 is “Yes,” the relativereflectance is outside of the threshold, and the process 1500 proceedsto calculating 1512 reflectance correcting capture settings, which forbrevity is also recited herein by the abbreviation “RCCS.” In anembodiment, operations in the comparing 1507B can provide, e.g., forinput to the RCCS calculation 1512, data regarding the deviation of therelative reflectance from the threshold. For purposes of description thedata will be referenced as “output reflectance deviation data.” Theoutput reflectance deviation data can include, for example, anarithmetic value or other characterization of the relative reflectanceobtained by the quantifying 1507A. The output reflectance deviation datacan also include, or the RCCS calculation 1512 can otherwise obtain, thecurrent threshold that was applied by the comparing 1507B. It will beunderstood that “RCCS,” as used in this disclosure, does not have orimport intrinsic meaning; it is an abbreviation for reading convenience.

In an embodiment, input to the RCCS calculation 1512 can also includedata characterizing the applied image capture settings used in capturingthe image determined by the comparing 1507B as not meeting thethresholds. It will be understood by persons of ordinary skill in therelevant arts, upon reading this disclosure in its entirety, thatimplementation of providing the applied image capture settings to theRCCS calculation 1512 can be, at least in part, application-specific.

Upon completing RCCS calculation 1512 the process 1500 can proceed tocommunicating 1514 the RCCS to the image capture resource. Specificimplementation of the communicating 1514, as described above forproviding applied image capture settings to the RCCS calculation 1512,can depend at least in part on respective sharing or independence ofcomputational resources between the process 1500 and the imagecapturing. Examples are described in greater detail in later sections ofthis disclosure.

After some duration of time, the process 1500 can receive 1516 from theimage capture resource a second captured image of the subject. Theprocess 1500, in response, can proceed to identifying 1518 whether thereflectance of the second captured image meets the reflectancethresholds. Operations in the identifying 1518 can be another instanceof the quantifying 1507A and comparing 1507B described above. Thresholdsapplied in this instance of the comparing 1507B can be identical to thethresholds applied to the first captured image. In an embodiment,thresholds applied to the second captured image can differ fromthresholds applied to the first captured image. For example, and withoutlimitation the process 1500 may be adapted to include, e.g., inassociation with RCCS calculation 1512 for the first captured image,communication with the biometric identification. In contemplatedimplementations in accordance with this disclosure, such communicationcan produce a selecting of an updated biometric algorithm. Based atleast in part on the updated biometric algorithm, threshold applied bythe comparing 1507B to the second captured image may differ fromthreshold applied to the first captured image.

Process 1500 flow after identifying 1518 whether the second capturedimage is outside of threshold depends at least in part on a result ofsaid identifying. In response to a negative result, i.e., theidentifying 1518 indicating the relative reflectance of the secondcaptured image is not outside the threshold, the process 1500 canproceed from the “No” outbranch of decision 1520 to the biometricidentification 1510. In response to a positive result at 1518, i.e.,determining the reflectance of the second captured image is outside thethreshold, the process 1500 can first proceed from the “Yes” outbranchof decision 1520 to an iteration decision 1522 of whether to performanother iteration of image capture. Logic specifications of theiteration decision 1522 can be application specific. Factors caninclude, for example and without limitation, whether this will be thefirst repeat iteration, tolerance to delays and reduction in biometricidentification throughput that may result from the iterations, as wellas burden on security personnel of resolution by intervention. Anotherfactor can be the reflectance deviation.

Assuming the iteration decision at 1522 is “Yes,” i.e., repeat anotheriteration, the process can return to RRCS calculation 1512 as describedabove. If the iteration decision 1522 is “No,” i.e., not to repeatanother iteration, the process 1500 can proceed, for example, to action1524, e.g., an intervention. Alternatively, the process 1500 can beconfigured such that, in place of action 1524, the process proceeds tobiometric identification 1510, irrespective of the captured image'sreflectance.

In embodiments, a system or device (e.g., an image capture device) isconfigured to capture multiple images so more than one image isavailable for skin reflectance analysis. In such embodiments, a systemresponse to a first image being out of tolerance for skin reflectancecan be to analyze another of the multiple images to determine if theother image is within tolerance and/or can be enhanced to be intolerance. The system, in other words, can be configured to iteratethrough images to obtain an image that is or can be enhanced to besuitable for biometric matching/identification. These additional imagesmay have been captured contemporaneously or substantiallycontemporaneously with the initial image examined for skin reflectancesuitability.

In some embodiments, systems include a variety of components that can beoperated in various configurations under control of the computing systemto select among various imaging devices, light sources, biometricmatching/identification algorithms and parameters. This can be donebased on analysis of the phenotypic information implemented by thecomputing resource. For example, the system, in response to determiningan image is unsuitable for biometric matching, can implement the variouscomponents to perform in a manner that is comparatively more likely toresult in acquisition of a suitable image. For example, in response todetermining a captured image in the visible spectrum is not suitable,the system can implement a combination of one or more of an infraredlight source, infrared camera and/or a biometric algorithm that areconfigured for use with infrared based imaging. Other techniques asunderstood by one of ordinary skill in the art can be implemented aswell to increase the likelihood of obtaining a suitable image. Forexample, the system may output prompts for the subject to increase thelikelihood that the subject is in an orientation that is more likely toresult in acquisition of a suitable image.

Computer System

FIG. 17 illustrates, in simplified schematic form a computer system 1702on which aspects of the present disclosure can be practiced. Thecomputer system 1702 can include a hardware processor 1703communicatively coupled to a memory 1704. The memory 1704 can include adata memory 1706 and an instruction memory 1708. Coupling of thehardware processor 1703 to the memory 1704 can be provided by a bus. Itwill be understood that the memory 1704 can be a distributed resource,with portions coupled to the hardware processor 1703 by local bus, localnetwork (LAN), or a wide area network (WAN), or combination of a localbus, LAN and WAN. It will be understood that the data memory 1706 andinstruction memory 1708 are logic functions and not necessarily discretehardware; e.g., they can be respectively assigned or allocated portionsof a shared memory resource.

The instruction memory 1708 can be configured to store, on at least anon-transitory computer readable medium as described in greater detailbelow, executable program code. The executable program code can beconfigured, in a logic sense, as modules that, when executed by thehardware processor 1703 can configure the hardware processor 1703 into alogic. The hardware processor 1703 may include multiple hardwareprocessors and/or multiple processor cores. The hardware processor 1703may include hardware processors from different devices that cooperate.

Relationship Between Hardware Processor and Executable Program Code

The relationship between the executable program code stored in theinstruction memory 1708 and the hardware processor 1703 is structural;the executable program code is provided to the hardware processor 1703by imparting various voltages at certain times across certain electricalconnections, in accordance with binary values in the executable programcode to cause the hardware processor 1703 to perform some action, as nowexplained in more detail.

The executable program code can comprise a sequence of instructions thatwhen executed by the computer system 1702 cause it to be configured in amanner consistent with this disclosure and operate as described herein.

For example, the instruction memory 1708 can store a reflectanceexecutable code 1710 that when executed by the hardware processor 1703can cause the processor to perform operations for quantifying therelative reflectance of a captured image, including but not limited tooperations and functionalities described in reference to the FIG. 3process 300 quantifying 304 or the FIG. 4 process 400 quantifying thecaptured image's relative reflectance. The relative reflectanceexecutable code 1710 is therefore alternatively referred to, and labeledaccordingly on FIG. 17, as “relative reflectance quantifying logic”1710. As visible in FIG. 17, the relative reflectance quantifying logic1710 can include component blocks or modules of executable code,respectively implementing component logic blocks that will be describedin greater detail in subsequent paragraphs.

The executable program code stored in the instruction memory 1708 canalso include reflectance thresholding executable code 1712 that whenexecuted by the hardware processor 1703 can cause the processor toperform operations that include comparing the relative reflectance of acaptured image, e.g., the relative reflectance generated by the relativereflectance quantifying logic 1710, against one or more thresholds andgenerating, based on a comparing against one or more thresholds, anindication of the captured image being suitable or not suitable forbiometric identification. Such operations and functionalities asdescribed above can include but are not limited to operations andfunctionalities described in reference to the FIG. 3 reflectancethreshold qualification 306. The reflectance thresholding executablecode 1712 is therefore alternatively referred to, and labeledaccordingly on FIG. 17, as “reflectance thresholding logic” 1712.

For brevity, other component blocks or modules of computer-executableinstructions will be referenced as “logic,” as each includes code thatwhen executed by the hardware processor 1703, can cause the processor toperform and provide functionalities of a particular logic.

The computing system 1700 can also include a communication controller1714 that can be under control of the processing system 1702 and can beadapted to receive an image 1716. The image 1716 can be a captured imageof a subject, such as a captured image received from the FIG. 1 digitalcamera 104. The communication controller 1714 can also be configured toprovide the received image 1716 to the computer system 1702 for storage.The storage can be, for example, in the data memory 1706 for furtherprocessing, e.g., by the relative reflectance quantifying logic 1710,for processes according to embodiments.

Executable program code stored in the instruction memory 1708 can alsoinclude biometric identifying logic 1720 that when executed by thehardware processor 1703 can cause the processor to perform logicfunctions of a matching between the captured image and a set or galleryof reference images such as a set of images in an image gallery. Thebiometric identifying logic 1720 an be configured to cause the hardwareprocessor 1703 to perform the biometric matching in response toindication, for example, by logic components within the relativereflectance quantifying logic 1710 and described in greater detaillater, that the relative skin reflectance value of the captured image iswithin the suitable range of relative skin reflectance values. In anembodiment, the biometric identifying logic 1720 can be adapted tooutput, by the communication controller 1714 as a message 1718, anidentification message identifying the subject. Referring to FIG. 14, anexample identification message can be an output identity indicationmessage 1432 indicating the subject as the individual associated withthe gallery image that matches the captured image with the highestbiometric comparison. In an aspect the biometric identifying logic 1720outputs an access control message that, directly or through anelectronic access control logic 1721, can be communicated to anelectronic access control device, e.g., the FIG. 13 electronicallyactuated access control device 1401. The signal, or command signal fromthe electronic access control logic 1721, can cause operation of theelectromechanical device, e.g., the electronically actuated accesscontrol device 1401, such as causing the device or another gate or otherphysical access control device to open.

In other examples, the hardware processor 1703 can output, e.g., basedon a biometric matching indication from the biometric identifying logic1720, an electronic indication associated with the (now matched)identity. Examples include displaying a yes/no or an “x” or checkmark ona communicatively coupled electronic display to indicate whether thesubject is to be permitted or denied, e.g., proceed to a testing centeror secured area such as a sterile security environment.

It will be understood that the above-described example features andoperations of the biometric identifying logic 1720 can implement or canbe components of an implementation of the FIG. 3 biometricidentification 310, can implement or can be components of animplementation of the FIG. 13 biometric identification 1310.

Executable program code stored in the instruction memory 1708 caninclude remediation select logic 1722 and can include post capturereflection correction logic 1724. Executable program code stored in theinstruction memory 1708 can include image capture remediation logic1726. The remediation select logic 1722 can be configured to cause, whenexecuted by the hardware processor 1703, the processor to perform andprovide functionalities including but are not limited to operations andfunctionalities described in reference to the FIG. 13 binary selecting1314 and the remediation selecting 1316. The post capture reflectioncorrection logic 1724, when executed by the hardware processor 1703, cancause the processor to perform and provide functionalities including butare not limited to operations and functionalities described in referenceto the FIG. 13 post capture reflection correction 1320A andcorresponding post processing determining 320B. The image captureremediation logic 1726, when executed by the hardware processor 1703,can cause the processor to perform and provide functionalities includingbut are not limited to operations and functionalities described inreference to the FIG. 3 image capture parameters adjust and retaking1318.

As described above, the relative reflectance quantifying logic 1710 caninclude component logic. In the FIG. 17 configuration, component logicof the relative reflectance quantifying logic 1710 can include facedetection logic 1728, boundary creation logic 1730, and image dividinglogic 1732. Configured as shown in FIG. 17, component logic of therelative reflectance quantifying logic 1710 can also include luminancevalue logic 1734, outlier discarding logic 1736, background extractionlogic 1738, and normalize luminance logic 1740.

The face detection logic 1728, when executed by the hardware processor1703, can cause the processor to perform operations and providefunctionalities including, but not limited to, operations andfunctionalities described in reference to the FIG. 3 face detecting 410.Such operations and functionalities can include but are not limited tothe three-rectangle feature operations described in reference to FIG. 9.The boundary creation logic 1730, when executed by the hardwareprocessor 1703, can cause the processor to perform and providefunctionalities including but not limited to operations andfunctionalities described in reference to the FIG. 6 creating 602 aboundary around the detected face region. The image dividing logic 1732,when executed by the hardware processor 1703, can cause the processor toperform and provide functionalities including but not limited tooperations and functionalities described in reference to the FIG. 7dividing 604 of an image into facial pixels 406 and remainder pixels414.

Referring to FIG. 17, the luminance value logic 1734, when executed bythe hardware processor 1703, can cause the processor to calculate aluminance value for at least some of the facial pixels within theboundary, e.g., the mask 802 boundary described in reference to FIG. 8A.The calculations can be an implementation, for example, of the FIG. 9calculating 902 of luminance values. In some embodiments, the luminancevalue logic 1734 can cause the hardware processor 1703 to calculate theluminance value based on a weighted sum of color component valuesassociated with pixels within the mask 802 boundary. It will beunderstood that logic similar to the luminance value logic 1734 can beused in instances in which phenotype traits other than luminancereflectance are being quantified. For example, spectral reflectancelogic can be used to calculate values of spectral reflectance phenomenaexhibited in a captured image. It will also be understood that luminancevalue logic 1734 can be configured for phenotype covariates.

The outlier discarding logic 1736, when executed by the hardwareprocessor 1703, can cause the processor to perform and providefunctionalities including a discarding of FIG. 6 facial pixels 406 whoseluminance values are outside of a threshold, to obtain facial skinpixels. For example, the outlier discarding logic 1736 can cause thehardware processor to discard outlier facial pixels among the facialpixels 406.

The outlier discarding logic 1736 operations and functionalities canimplement, without limitations, operations described above in referenceto the selecting 418 of facial skin pixels 420, or in combination with,operations and functionalities described above in reference to the FIG.8 discard 804 of outlier pixels.

The FIG. 17 background extraction logic 1738 component of the relativereflectance quantifying logic 1710, when executed by the hardwareprocessor 1703, can cause the processor to perform and providefunctionalities including but not limited to operations andfunctionalities described above in reference to the obtaining 404 offacial pixels 406 and background pixels 408, or in combination with,operations and functionalities described above in reference to the FIG.11 obtaining 1102 background pixels.

The FIG. 17 normalize luminance logic 1740, when executed by thehardware processor 1703, can cause the processor to perform operationsand provide functionalities including but not limited to calculating amean of the background pixels, or a portion of the background pixelsthen, based at least in part on the mean of the background pixels orportion thereof, normalizing the luminance values calculated by the FIG.17 luminance value logic 1734. The result of the normalizing can benormalized luminance values. For purposes of description the mean of thebackground pixels or portion thereof can be referenced as a “firstmean.” The normalize luminance logic 1740 is representative of logicused to normalize data of interest (e.g., luminance values from facialskin reflectance) based on other data (e.g., background data) to correctfor acquisition issues so the resultant data (in the case of skinreflectance, normalized skin data derived from data for facial skinpixels and background pixels) more accurately represents the data ofinterest in comparison to the raw data that has not been so transformed.In embodiments the normalize luminance logic 1740 can divide luminancevalues of the facial skin pixels by a mean of the intensities of thebackground pixels (the first mean) to obtain normalized luminance valuesof the facial skin pixels.

The relative reflectance quantifying logic 1710 can include relativereflectance computation logic that can calculate a mean of thenormalized luminance values. For purposes of description the mean of thenormalized luminance values can be referenced as a “second mean.” Therelative reflectance computation logic can compute the relativereflectance as, or as a value based on, the second mean.

This image dividing logic 1732 can implement instructions that permitthe computer system 1702 to operate on facial pixels as shown in FIG. 8and (separately or coextensively albeit with different processingresources) on the background pixels shown and discussed in conjunctionwith FIG. 11.

Background extraction logic 1738 comprises instructions that select fromthe remainder pixels a set of background pixels, as previouslyillustrated and described. Those of skill in the art will appreciatethat the background obtaining logic 1738 is optional logic that can beused in a variety of situations to obtain relative values that, to someextent, may be used to address image acquisition phenomena exhibited ina captured image. For example, approaches that make use of spectralreflectance may benefit from such image processing techniques.

Relative reflectance quantifying logic 1710 comprises instructions thatcalculate a relative skin reflectance value for the captured image froma mean of the normalized luminance values of the facial skin pixels (thesecond mean). As discussed above other phenotypic characteristics mayimplement similar approaches to derive phenotypic data that is relativeto other collected information.

The image processing logic, as shown in FIG. 17 and discussed above, cantransform the computer system 1702 into a special-purpose computingsystem that functions to conserve processor use, in an embodiment. Forexample, when relative skin reflectance logic detects that the capturedimage is unsuitable for biometric comparison, the computer system 1702is configured to not undertake resource-intensive, biometric matchingsince the outcome is unlikely to result in a suitable outcome, e.g.,yes/no. This conserves system resources and, where a system offers theopportunity to retake the captured image, preserves processor resourcesfor biometric data that have an improved likelihood of a correct matchor, at least, a decreased likelihood of a non-conclusive result. In sucha situation, where the captured image is unsuitable for use or cannotreadily be enhanced for use, other steps can be taken such as performingnon-automated identification.

The hardware processor 1703 may be thought of as a complex electricalcircuit that is configured to perform a predefined set of basicoperations in response to receiving a corresponding basic instructionselected from a predefined native instruction set of codes.

The predefined native instruction set of codes is specific to thehardware processor; the design of the processor defines the collectionof basic instructions to which the processor will respond, and thiscollection forms the predefined native instruction set of codes.

A basic instruction may be represented numerically as a series of binaryvalues, in which case it may be referred to as a machine code. Theseries of binary values may be represented electrically, as inputs tothe hardware processor, via electrical connections, using voltages thatrepresent either a binary zero or a binary one. These voltages areinterpreted as such by the hardware processor.

Executable program code may therefore be understood to be a set ofmachine codes selected from the predefined native instruction set ofcodes. A given set of machine codes may be understood, generally, toconstitute a module. A set of one or more modules may be understood toconstitute an application program or “app.” An app may interact with thehardware processor directly or indirectly via an operating system. Anapp may be part of an operating system.

Computer Program Product

A computer program product is an article of manufacture that has acomputer-readable medium with executable program code that is adapted toenable a processing system to perform various operations and actions.

A computer-readable medium may be transitory or non-transitory.

A transitory computer-readable medium may be thought of as a conduit bywhich executable program code may be provided to a computer system, ashort-term storage that may not use the data it holds other than to passit on.

The buffers of transmitters and receivers that briefly store onlyportions of executable program code when being downloaded over theInternet is one example of a transitory computer-readable medium. Acarrier signal or radio frequency signal, in transit, that conveysportions of executable program code over the air or through cabling suchas fiber-optic cabling provides another example of a transitorycomputer-readable medium. Transitory computer-readable media conveyparts of executable program code on the move, typically holding it longenough to just pass it on.

Non-transitory computer-readable media may be understood as a storagefor the executable program code. Whereas a transitory computer-readablemedium holds executable program code on the move, a non-transitorycomputer-readable medium is meant to hold executable program code atrest. Non-transitory computer-readable media may hold the software inits entirety, and for longer duration, compared to transitorycomputer-readable media that holds only a portion of the software andfor a relatively short time. The term, “non-transitory computer-readablemedium,” specifically excludes communication signals such as radiofrequency signals in transit.

The following forms of storage exemplify non-transitorycomputer-readable media: removable storage such as a universal serialbus (USB) disk, a USB stick, a flash disk, a flash drive, a thumb drive,an external solid-state storage device (SSD), a compact flash card, asecure digital (SD) card, a diskette, a tape, a compact disc, an opticaldisc; secondary storage such as an internal hard drive, an internal SSD,internal flash memory, internal non-volatile memory, internal dynamicrandom-access memory (DRAM), read-only memory (ROM), random-accessmemory (RAM), and the like; and the primary storage of a computersystem.

Different terms may be used to express the relationship betweenexecutable program code and non-transitory computer-readable media.Executable program code may be written on a disc, embodied in anapplication-specific integrated circuit, stored in a memory chip, orloaded in a cache memory, for example. Herein, the executable programcode may be said, generally, to be “in” or “on” a computer-readablemedia. Conversely, the computer-readable media may be said to store, toinclude, to hold, or to have the executable program code.

Creation of Executable Program Code

Software source code may be understood to be a human-readable,high-level representation of logical operations. Statements written inthe C programming language provide an example of software source code.

Software source code, while sometimes colloquially described as aprogram or as code, is different from executable program code. Softwaresource code may be processed, through compilation for example, to yieldexecutable program code. The process that yields the executable programcode varies with the hardware processor; software source code meant toyield executable program code to run on one hardware processor made byone manufacturer, for example, will be processed differently than foranother hardware processor made by another manufacturer.

The process of transforming software source code into executable programcode is known to those familiar with this technical field as compilationor interpretation and is not the subject of this application.

User Interface

A computer system may include a user interface controller under controlof the processing system that displays a user interface in accordancewith a user interface module, i.e., a set of machine codes stored in thememory and selected from the predefined native instruction set of codesof the hardware processor, adapted to operate with the user interfacecontroller to implement a user interface on a display device. Examplesof a display device include a television, a projector, a computerdisplay, a laptop display, a tablet display, a smartphone display, asmart television display, or the like.

The user interface may facilitate the collection of inputs from a user.The user interface may be graphical user interface with one or more userinterface objects such as display objects and user activatable objects.The user interface may also have a touch interface that detects inputwhen a user touches a display device.

A display object of a user interface may display information to theuser. A user activatable object may allow the user to take some action.A display object and a user activatable object may be separate,collocated, overlapping, or nested one within another. Examples ofdisplay objects include lines, borders, text, images, or the like.Examples of user activatable objects include menus, buttons, toolbars,input boxes, widgets, and the like.

Communications

The various networks are illustrated throughout the drawings anddescribed in other locations throughout this disclosure, can compriseany suitable type of network such as the Internet or a wide variety ofother types of networks and combinations thereof. For example, thenetwork may include a wide area network (WAN), a local area network(LAN), a wireless network, an intranet, the Internet, a combinationthereof, and so on. Further, although a single network is shown, anetwork can be configured to include multiple networks.

Conception and Development

Systems were evaluated based on their respective acquisition andattempted matching of facial images from a diverse population of 363subjects in a controlled environment. Biometric performance was assessedusing both efficiency (transaction times) and accuracy (mated similarityscores using a representative algorithm).

An automatic method for measuring relative facial skin reflectance usingsubjects' enrollment images was developed. The method quantified theeffect of this metric and other demographic covariates on performancelinear modeling. Both the efficiency and accuracy of the testedacquisition systems were affected by multiple demographic covariatesincluding age, eyewear, and height.

Reflectance had the strongest net linear effect on performance. Linearmodeling showed that lower skin reflectance was associated with lowerefficiency (higher transaction times) and accuracy (lower similarityscores). Skin reflectance was also a statistically better predictor ofthese effects than self-identified labels.

Unlike other covariates, the degree to which skin reflectance alteredaccuracy varied based on the system. FIG. 18 Graph B illustrates thatthe size of this skin reflectance effect was inversely related to theoverall accuracy of the system such that the effect was almostnegligible for the system with the highest accuracy. These resultssuggested that, in evaluations of biometric accuracy, the magnitude ofdiffering effects depends on image acquisition.

The inventors carried out a large-scale scenario study. The study wasdesigned to simulate a high-throughput biometric identification process.The study involved multiple facial recognition systems and measured theefficiency and effectiveness with which the systems acquired and matchedface images from differing populations.

To understand the factors affecting the performance of face acquisitionsystems, the study gathered images and associated metadata. To evaluatethe samples, the study used a reference algorithm to find the rank-onemated similarity score against two separate galleries, a gallery ofsame-day images, and a gallery of up to 4-year-old historic images.

A methodology for calculating the relative skin reflectance of eachsubject, using their same-day gallery images, is described below.

Models for the statistical relationship between the eleven testedbiometric acquisition systems, mated similarity scores, and thecollected/calculated covariates are discussed. The covariates include,among others, reflectance, population identifications, eyewear, age,height, and weight. The results show that biometric system performanceis strongly affected by skin reflectance though this dependency variesbase on the system.

The systems were tested using 363 volunteer subjects. Subjects selectedpopulation categories based on U.S. Census categories. FIG. 18 Graphs A,B, C, D, E, and F show distributions of variables self-reported by thetest subjects.

FIG. 19 shows a test subject queue state on a schematic of an exampletest system environment. The test system environment included adedicated station 1902, and a subject queue 1904 at the station. Staff1906 established the ground-truth identity of the subjects by scanning1908 a QR code printed on the subject's wristband, subjects entered thetest station, triggering a beam break BB1, subjects interacted with theface capture system, which submitted images (biometric samples) forstorage, subjects exited the test station, triggering a beam break BB2.The duration of the subject's interaction with the system was measuredas the difference in time between BB2 and BB1 and the images submittedby the systems were used to analyze biometric performance.

The test process and evaluation were designed to provide a systematic,repeatable framework for evaluating the acquisition speed and matchingperformance of the systems. Subjects were briefed as to the purpose ofthe tests. Subjects were asked to comply with all instructions presentedby the systems but were not specifically instructed regarding themechanistic details of the individual systems.

Subjects were organized into groups of approximately 15. Subjectsentered the respective stations one-at-a-time after their ground truthidentity was recorded. The order in which the groups and systemsinteracted were counterbalanced. The systems operated autonomously.Image submissions were made by each station in real time via a common,web-based application program interface (API).

Prior to participation, subjects were enrolled into a same-day faceimage gallery. Subjects stood in front of an 18% neutral graybackground. Diffuse illumination was measured at 600-650 lux. A LogitechC920 camera at a 1-meter standoff (resolution: 1920×1080) was used tocapture the reference image. Subjects were instructed to remove any hatsor glasses and assume a neutral expression. Image quality issues wereaddressed by reacquiring images as appropriate. This resulted in asame-day face image gallery of 363 face samples from 363 unique people.

A historic reference face image gallery of 1,848 samples from 525 uniquepeople (average of 3.5 images per person) was assembled. The sampleswere acquired over the course of four years using a variety of camerasincluding digital single lens reflex (DSLR) cameras, web cameras, andcameras embedded in biometric devices. The historic gallery containedimages for 326 of the 363 test subjects that participated in theevaluation as well as 199 “distractors” or out of gallery subjects.

Performance of a facial recognition algorithm can be dependent on thepixel intensities of the provided facial images. In facial images,factors affecting skin pixel intensity can include (i) physicalproperties of the skin and underlying tissue (layers, absorbers, andscattering coefficients); (ii) physical properties of the skin surface(specular reflectance); and (iii) imaging artifacts (incident lightintensity, camera gain).

The FIG. 20 process 2000 included enrollment photo 2001 followed by facefinding 2002 then, for reasons including but not limited to computationefficiency, proceeded using parallel computation processes. Using thearrangement of FIG. 20, the computations will be referenced as an “upperpath” 2004 and a “lower path” 2003. The upper path 2004 includescircular mask 2004A, luminance calculation 2004B, Z-score outlierremoval 2004C, and face color averaging 2004D. The lower path 2003,proceeding from the face finding 2002, includes background sampling2003A, and background averaging 1903B. The process 2000 then appliedbackground correction 2006 to the face color averaging 1904D, using thebackground averaging 2003B, producing normalized (R,G,B) color values2008.

This method is distinct from non-linear color space transformations likeCIELab color or YCbCr, in that the method's objective is not to measureskin color, which is a non-linear perceptual phenomenon captured bycolor spaces optimized for human perception, but to measure the physicalskin properties, which can rely on light intensity measurements atspecific wavelengths.

Because some image artifacts are multiplicative in nature and a constantreference region in the neutral 18% gray background existed, the average(R, G, B) color values from these facial skin pixels can be correctedfor artifacts by divisive normalization using background regionsselected from gray areas around the face. This operation corrects forcamera exposure and incident light intensity. Other operations can beapplied, for example, to address variations in shadows across the faceor specular reflection, and to correct for camera color balance.

After background correction and outlier removal, the resulting (R, G, B)values can depend primarily on the physical properties of the skin andare proportional to the amount of incident light reflected from theface. The methodology for calculating this metric was based on thespecific collection conditions used, namely, the consistent lighting,the same acquisition camera, and the constant neutral gray background.This method provided us with an estimate of the physical properties ofthe respective subject's skin obtained on independent samples.

One approach implemented Principal Components Analysis (PCA) on the (R,G, B) color values. The first two principal components (PC1 and PC2)explained 96.1% and 3.4% of the variance in (R, G, B) color values,respectively, collectively explaining 99.5% of the total color variance.This may relate to melanin and hemoglobin being the two main absorbersof light in skin, with most of the variation in reflectance across skintypes due to melanin. This final metric, namely the position of thesubject along PC1, is referred to here as a measure of their relativeskin reflectance (e.g., reflectance).

Face images acquired by each system were matched using acommercially-available biometric algorithm against both the same-day andhistoric galleries. The set of mated similarity scores against thesame-day gallery used samples from all 363 test subjects. Thecorresponding set for the historic gallery used samples from the 326test subjects who had corresponding images in the historic gallery. Forsystems s∈S returning multiple face images, i∈I, mated similarity scoreswere examined for the last image acquired, (i)∈I, within the 20 secondtime interval following entry beam-break. Same-day mated similarityscores for subject j∈J is denoted Φ_(j,s) ^(sd)=ϕ_((i)). For thehistoric gallery, which contained i∈I gallery images for each subjectj∈J, the top mated similarity score Φ_(j,s) ^(hist)=max_(i∈I)ϕ_(i) wasused for statistical analysis. Some systems occasionally had technicalissues or acquired images for individuals in the background causing themto submit a photo for the next or previous subject in the queue. Theprocedure used in the experiment therefore removed images for which therank-one similarity score was higher than the mated similarity score.This occurred in fewer than 30 transactions across the systems (e.g.,less than 1% of collected data was affected/removed) and manual reviewindicated that most were artifacts introduced during testing.

To estimate the overall average effects of factors, linear regressionwas applied to the subject's all-system average historic and same-daymated similarity scores Φ as well as average transaction times Ψ.Specifically, for each subject j using all N=11 systems, s, the averagemated similarity score Φ to the historic gallery as

${\overset{\_}{\Phi}}_{j} = {\frac{1}{N}{\sum\limits_{s = 1}^{s = N}\Phi_{j,s}^{hist}}}$

and to the same-day gallery as

${\overset{\_}{\Phi}}_{j} = {\frac{1}{N}{\sum\limits_{s = 1}^{s = N}\Phi_{j,s}^{sd}}}$

was computed. In constructing the linear model, eleven demographiccovariates were considered, including three categorical variables. Thecontinuous variables age, height, weight, and skin reflectance werenormalized prior to fitting according to z=(x−μ_(x))/σ_(x) and includedtheir squared transformations in the full model for each responsevariable Θ_(j)∈{Ψ _(j),Φ _(j)}. The inclusion of interaction terms,which could lead to over-fitting, was not considered in this analysis.

$\begin{matrix}{\Theta_{j} = {\beta_{0} + {\beta_{1}gender_{j}} + {\beta_{2}eyewear_{j}} + {\beta_{3}race_{j}} + {\beta_{4}age_{j}} + {\beta_{5}age_{j}^{2}} + {\beta_{6}height_{j}} + {\beta_{7}height_{j}^{2}} + {\beta_{8}weight_{j}^{2}} + {\beta_{10}reflectance_{j}} + {\beta_{11}reflectance_{j}^{2}} + \epsilon_{j}}} & (1)\end{matrix}$

Model parameters β were estimated using ordinary least squares (OLS)fitting. The optimal all-system model was defined as one that minimizesthe Akaike Information Criteria, AIC=2k−2 ln({circumflex over (L)}),where k represents the number of estimated parameters in the model and{circumflex over (L)} represents the maximum value of the model's fittedlikelihood. Akaike Information Criteria (AIC) measures the goodness offit of the model while discouraging over-fitting with a penalty forincreasing the number of model parameters k. To find the optimal models,the full model was fit with all eleven covariates. A step-wise procedurewas then applied in both directions using the step AIC( ) function inthe R package MASS. This procedure was applied to both the historic andsame-day average mated similarity scores and average transaction times.Equation 2 describes a final optimal model with k−1 covariates selected,for the j^(th) subject.

$\begin{matrix}\left. \begin{matrix}{x_{j} = \left\lbrack {x_{1,j},x_{2,j},{\ldots\mspace{14mu} x_{{k - 1},j}}} \right\rbrack} \\{\beta = \left\lbrack {\beta_{1},\beta_{2},{\ldots\mspace{14mu}\beta_{k - 1}}} \right\rbrack} \\{{\overset{\_}{\Theta}}_{j} = {\beta_{0} + {\beta^{T}x_{j}} + \epsilon_{j}}}\end{matrix} \right\} & {{Equation}\mspace{14mu}(2)}\end{matrix}$

The accuracy of model fits was assessed through residual analysis. Forthree optimal all-system models, the study found the residuals deviatedfrom normality, with noticeable deviations present in the QQ plots ofthe response variables Θ_(j) (data not shown). Confidence intervals formodel parameter estimates were therefore obtained using a bootstrappingtechnique instead of relying on the standard error. One thousandbootstrap samples were generated and the bias-corrected bootstrappedconfidence intervals or the BCα for each of the fitted coefficients inthe optimal model were calculated.

The model selection approach showed that some covariates did not improvemodel fit sufficiently as judged using AIC and are therefore excludedfrom the optimal model. The non-parametric technique of cross-validationwas used to independently confirm the optimality of select covariatesincluded in the optimal model. Tenfold cross-validation was used andcompared the cross-validated R² of the optimal model to a model where acovariate present in the optimal model is replaced by an alternatecovariate that is not present in the optimal model. Since the exact foldcompositions and therefore the cross-validated R² values are dependenton a random seed, this procedure was executed with 100 randomly drawnstarting seeds to compute the mean and 95% confidence intervals for thecross-validated R² values.

Average linear regression models were applied to ascertain effects ofdifferent populations on all-system average mated similarity scores andaverage transaction times. However, because the 363 subjects interactedwith the systems studied, it was examined whether mated similarityscores for images acquired on different systems had distinct demographiccovariate effects. To model these effects, linear mixture modeling wasapplied with the system s as the random effect. To start, demographiccovariates were retained in the optimal model from Equation 2 as fixedeffects. This allowed for modeling of the response variable byestimating both the variance across all systems (fixed effects: β₀ andβ^(T)) and the variance between different systems (random effects:β_(0,s) and β_(s) ^(T)) according to Equation 3 where y is the set of mselected system-specific slope covariates and β_(s) are thecorresponding parameters.

$\begin{matrix}\left. \begin{matrix}{y_{j} = \left\lbrack {y_{1,j},y_{2,j},{\ldots\mspace{14mu} y_{m,j}}} \right\rbrack} \\{\beta_{s} = \left\lbrack {\beta_{1,s},\beta_{2,s},{\ldots\mspace{14mu}\beta_{m,s}}} \right\rbrack} \\{\Theta_{j,s} = {\beta_{0} + {\beta^{T}x_{j}} + \beta_{0,s} + {\beta_{s}^{T}y_{j}} + \epsilon_{j} + \gamma_{s}}}\end{matrix} \right\} & {{Equation}\mspace{14mu}(3)}\end{matrix}$

Starting with only the fixed effects model, a system-specific slopeβ_(0,s) was added. If this reduced AIC, it signified that there arestatistical performance differences between systems. Then, given theintercept model that includes β_(0,s), a forward model selectionapproach was used to identify the mixed individual effects that continueto minimize AIC, adding each demographic covariate (y_(j)) one at atime. A reduction in AIC for a given demographic covariate signifies theinclusion of a system-specific coefficient for this variable improvesmodel fitness and thus, there are notable performance differencesbetween stations for this demographic factor. This procedure wasperformed for the historic gallery similarity scores. Since the goal ofthis analysis was to estimate the system-specific effects, all modelparameters β were estimated by maximizing the restricted maximumlikelihood (REML).

The effects of skin reflectance on similarity scores were measured usinglinear modeling. To identify the overall effect of subject demographicson similarity scores, an average similarity score for each subject onall eleven tested systems was computed. To examine longitudinal changesin appearance (e.g., changes in attire, self-styling, and ageing),separate models were fit to average similarity scores obtained frommatching images to the historic and to the same-day galleries. Startingwith a model including eleven demographic covariates (Equation 1), anAIC-based model selection approach was used to find an optimal modelincluding only those demographic covariates that improved model fitwhile minimizing the number of model parameters. Following modelselection, the 95% bootstrapped, bias-corrected confidence intervals(BCα) were computed for each parameter.

FIG. 18 shows average mated similarity scores varying in relation toskin reflectance and gender. Points show the average mated similarityscores for female and male subjects, with lighter points showing averagemated similarity scores for individual subjects and darker pointsshowing the grand average of scores across subjects, binned byreflectance quartile. Lines indicate optimal age and gender model fits,fixing other factors constant at the average value of the subjectpopulation in each facet. The box plots within the facet show marginaldistributions of similarity scores by self-reported gender.

Plotting average mated similarity scores as a function of skinreflectance, age bins, and gender, as shown in FIG. 19, showed thatscores tended to be lower for subjects with lower reflectance values forboth the historic and same-day galleries. For the historic gallery,scores for male subjects were notably higher than for female subjects.For the same-day gallery, however, male and female subjects tended tohave similar score distributions. Further, scores for younger subjectstended to be lower for the historic gallery. The linear fits depicted inFIG. 19 do not include the effect of eyewear; those who reported wearingsome form of eyewear had lower scores for both same-day and historicgalleries.

Table 1 below shows parameter estimates for the optimal models, fittingall-system average same-day and historic similarity scores.

TABLE 1 Net Covariate Estimate BCα Range Effect Optimal Historic Model{circumflex over (β)}₀ Intercept 0.830 (0.817, 0.841) NA NA {circumflexover (β)}₁ Gender 0.034 (0.022, 0.048)  {0,1} 0.034 {circumflex over(β)}₂ Eyewear −0.025 (−0.039, −0.012)  {0,1} 0.025 {circumflex over(β)}₄ Age 0.007 (0.001, 0.013) (−1.47, 3.09) 0.032 {circumflex over(β)}₇ Height² −0.006 (−0.011, 0.0002) (0.0004, 7.43)  0.041 {circumflexover (β)}₁₀ Reflectance 0.016 (0.009, 0.024) (−2.41, 2.39) 0.075 OptimalSame-Day Model {circumflex over (β)}₀ Intercept 0.894 (0.885, 0.900) NANA {circumflex over (β)}₁ Gender −0.019 (−0.029, −0.009)  {0,1} 0.019{circumflex over (β)}₂ Eyewear 0.005 (0.0001, 0.011)  (−2.33, 2.73)0.027 {circumflex over (β)}₄ Age −0.004 (−0.008, 0.001)  (0.0004, 7.43) 0.027 {circumflex over (β)}₇ Height² −0.005 (−0.011, 0.001)  (−2.61,3.50) 0.031 {circumflex over (β)}₁₀ Reflectance 0.010 (0.006, 0.016)(−2.41, 2.39) 0.050

Parameters not included in the optimal model are not shown (see Equation1). 95% confidence intervals BCα are estimated using bootstrap. Neteffect of the covariate is estimated as the product of {circumflex over(β)} and the magnitude of the observed range of values for the covariate|max−min|. The units of similarity scores are arbitrary.

Table 1 shows the estimates, 95% confidence intervals (BCα), and the neteffect of each coefficient (β) in the optimal historic and same-daygallery model of mated similarity scores. The net effect of a covariatewas estimated as the product of {circumflex over (β)} and the magnitudeof the observed range of values for the covariate |max−min|. By thismetric, reflectance was the covariate with the single greatest neteffect on mated similarity scores with a net effect equal to roughly 10%of the intercept value of the historic similarity scores and roughly 6%of the intercept of the same-day similarity scores.

Consistent with visual impressions from FIG. 22, fitted parameterestimates for the historic gallery model indicated that average matedsimilarity scores decreased significantly for younger subjects, thosewho identified as female, those with lower skin reflectance and thosewho reported eyewear. The effect of height on mated similarity scoreswas negative, suggesting deviations from average height decreased thescores. BCα for this factor, however, overlapped 0 in both the same-dayand historic model. The effects of height, eyewear, and skin reflectancealso appeared in both models. Notably, age and gender only appeared ascovariates in the historic model, indicating that these covariates didnot influence same-day similarity scores. Weight was present in thesame-day optimal model, but BCα for this factor overlapped 0.

The effects of demographic factors on the time required for subjects tocomplete biometric transactions was also measured and found largeeffects for subjects with eyewear and lower skin reflectance.Transaction times were measured at the respective stations as the timeinterval between subjects crossing the entry and exit beam breaks, whichincluded all interactions with the biometric face capture system, asshown in FIG. 19. Linear modeling was used to measure the net effect ofdemographic covariates on all-system average transaction times. Table 2shows the estimated coefficients along with their 95% confidenceintervals (BCα) and net effect for each covariate in the optimaltransaction time model.

TABLE 2 Net Covariate Estimate BCα Range Effect Optimal Time Model{circumflex over (β)}₀ Intercept 6.161 (5.933, 6.417) NA NA {circumflexover (β)}₁ Gender −0.238 (−0.473, 0.029)   {0,1} 0.238 {circumflex over(β)}₂ Eyewear 0.317 (0.050, 0.557)  {0,1} 0.317 {circumflex over (β)}₄Age 0.250 (0.114, 0.387)  (−1.47, 3.09) 1.139 {circumflex over (β)}₅Age² 0.134 (0.018, 0.270) (0.0001, 9.53) 1.257 {circumflex over (β)}₇Height² 0.116 (0.021, 0.223) (0.0004, 7.43) 0.860 {circumflex over(β)}₁₀ Reflectance −0.258 (−0.384, −0.144)  (−2.41, 2.39) 1.235

Transaction times increased significantly for subjects who reportedeyewear, those with lower skin reflectance, and had a complexrelationship with subject height and age (both linear and quadraticfactors included). Again, skin reflectance was the factor with thegreatest net effect, this time on transaction time, with a net effect of20% on the intercept transaction time of 6.2 seconds. These resultsindicate that demographic factors significantly affected not onlybiometric matching effectiveness, but also the efficiency of biometricacquisitions.

Table 2, above, gives parameter estimates for optimal models, fittingall-system average transaction times. Parameters not included in theoptimal model are not shown (see Equation 1). 95% confidence intervalsBCα are estimated using a bootstrap approach. Net effect of thecovariate is estimated as the product of {circumflex over (β)} and themagnitude of the observed range of values for the covariate |max−min|.The unit of transaction time is seconds.

The optimal models for average historic and same-day similarity scoresas well as average transaction times presented in Table 1 and Table 2all retained skin reflectance as an explanatory variable. This suggestedthat the new phenotypic metric of relative skin reflectance is a betterpredictor of similarity score and transaction time than demographiccategories. To confirm this finding, cross-validated R2 for optimalmodels that include reflectance and non-optimal models were compared.

Referring to FIG. 22, the net effect of relative skin reflectance iscompared for systems with lower historic mated similarity scores. FIG.22 Graph A shows the mated similarity scores by acquisition system. Ineach facet, colored points plot average scores across subjects binned byreflectance quartile. Facets are arranged based on the averagesimilarity score produced by the acquisition system. FIG. 22 Graph Bshows linear modeling estimates, of the reflectance net effect on matedsimilarity scores (β₁₀+β_(10,s))ΔReflectance (where ΔReflectance is thespan of observed reflectance values) plotted as a function ofsystem-specific intercept (β₀+β_(0,s)). Note the decreasing net effectof reflectance with the increasing level of performance (intercept).Points marked in red correspond to stations with the highest and lowestintercepts detailed in B. FIG. 22 Graph C shows a distribution of matedsimilarity scores for systems marked red in B. Light points denoteindividual subject mated similarity scores. Dark colored points denoteaverage scores across subjects binned by reflectance quartile. Linesindicate optimal age and gender model fits, fixing other factorsconstant at the average value of the subject population in each facet.Note the higher net effect of reflectance on mated similarity scoressome systems as well as lower overall mated similarity scores.

As shown in FIG. 22 Graph A, it was found that average similarityscores, and the net effect of demographic covariates on historicsimilarity scores could vary between systems. To compare demographiceffects across systems, the mated similarity scores of probes tohistoric gallery images were modeled across all tested systems usingmixed effects models. To identify those demographic covariates thatvaried between systems, model selection was performed using AIC,starting with the baseline optimal model selected for explainingall-system average similarity scores. Table 3 also shows several mixedeffects models, namely the random intercept model (Optimal+{circumflexover (β)}_(0,s)) and models with random slopes included(Optimal+{circumflex over (β)}_(0,s)+β_(n,s)covariate_(j)+γ_(s)). FromTable 3, note that AIC was reduced (i.e., the model was improved) withthe addition of the random intercept {circumflex over (β)}_(0,s),indicating that there were performance differences between systems. AICwas further reduced only with the addition of a random slope parameteron reflectance {circumflex over (β)}_(10,s), indicating thatreflectance, but not other covariates, had different effects on theperformance of different systems.

TABLE 3 Historic Model AIC Optimal −6219.808 Optimal + β_(0, s) + γ_(s)−7069.695 Optimal + {circumflex over (β)}_(0, s) + β_(1, s)gender_(j) +γ_(s) −7065.695 Optimal + {circumflex over (β)}_(0, s) +β_(2, s)eyewear_(j) + γ_(s) −7065.723 Optimal + {circumflex over(β)}_(0, s) + β_(4, s)age_(j) + γ_(s) −7069.181 Optimal + {circumflexover (β)}_(0, s) + β_(7, s)height_(j) ² + γ_(s) −7067.857 Optimal +{circumflex over (β)}_(0, s) + β_(10, s)reflectance_(j) + γ_(s)−7074.124

Table 3 shows AIC values for fixed and mixed effects models fitted tohistoric mated similarity scores. The optimal historic model is as inTable 1. {circumflex over (β)}_(0,s) is the random system intercept andβ_(n,s) are the random system slopes for each named covariate.

The mixed effect modeling approach shows that a model which includes 1)the original fixed effects, 2) the system-specific intercept, and 3) asystem-specific slope associated with reflectance, minimized the AIC.The coefficients of this optimal model are shown in Table 4. The fixedeffect coefficients of the selected mixed effect model are approximatelyequal to the fixed effect coefficients of the selected average model.This demonstrates a consistency in modeling and that the average modelin Table 1 is not unduly affected by system-specific outliers.

TABLE 4 Covariate Estimate CI Range {circumflex over (β)}₀ Intercept0.833 (0.806, 0.860) NA {circumflex over (β)}₇ Height² −0.006 (−0.008,−0.003) (0.0004, 7.43)  {circumflex over (β)}₁ Gender 0.034 (0.028,0.039) {0,1} {circumflex over (β)}₂ Eyewear −0.023 (−0.029, −0.017){0,1} {circumflex over (β)}₄ Age 0.007 (0.005, 0.010) (−1.47, 3.09) {circumflex over (β)}₁₀ Reflectance 0.014 (0.011, 0.018) (−2.41, 2.39) {circumflex over (β)}_(0, s) System * *  (0.71, 0.88) Intercept{circumflex over (β)}_(10, s) System * *  (0.01, 0.03) Reflectance

Table 4 shows parameter estimates and confidence intervals of themixed-effects model fitted to mated similarity scores across systems.{circumflex over (β)}_(1,s) represents the random intercept parameterand {circumflex over (β)}_(2,s) represents the random slope parameter,which vary by system s. Mixed effects parameter estimates and associated95% confidence intervals (marked with *) are plotted in FIG. 21.

In the selected model, the difference in overall performance is capturedby the system-specific intercept {circumflex over (β)}_(0,s) andsystem-specific variation from reflectance is captured by thereflectance slope β_(10,s). Plotting the net effect of system-specificreflectance ((β₁₀+β_(10,s))*Δ_(Reflectance), where Δ_(Reflectance) isthe span of observed reflectance values) on mated similarity scoresversus the system-specific intercept of each system showed that systemswith lower overall levels of performance also showed a greater neteffect of reflectance on mated similarity scores (FIG. 22, Graph B). Inother words, better overall quality acquisition systems can maintainhigh performance across the full range of skin reflectance values.Systems 3 and 7 show the largest difference between system-specificintercepts, with a 0.16 difference in mated similarity scores. Thisvalue is comparable to the largest net effect of reflectance—adifference of 0.12 in mated similarity score between the highest andlowest reflectance observed on System 7. These differences areillustrated in FIG. 22, Graph C, which allows visual inspection of thenet effect of reflectance and acquisition system on mated similarityscores.

These analyses show that some factors influenced both the speed andaccuracy of the evaluated systems. For example, modeling showed thatmated similarity scores were higher for men versus women, for olderversus younger people, for those without eyewear, and those withrelatively lighter skin. Of the different covariates examined, thecalculated measure of skin reflectance had the greatest net effect onaverage biometric performance (Table 1 and Table 2). For matedsimilarity scores, the fixed effects of gender, eyewear, and age wereconstant across the tested systems while the magnitude of the randomeffect of skin reflectance varied between systems in a manner inverselycorrelated with overall system accuracy, as seen in FIG. 22.

The inverse relationship between the net effect of skin reflectanceobserved for a system and that system's overall performance (see Graph Bin FIG. 22) has implications. The data shows that systems with betteroverall performance had improved performance most for individuals withlower skin reflectance. Thus, a woman with lower skin reflectance usinga superior system was more likely to match her mated gallery images thana man with higher skin reflectance using an inferior system.

Another consequence of these results is that deploying a superiorbiometric acquisition system may significantly reduce or eliminateperformance differences between some demographic groups. Indeed, in thedata set, image quality varied between acquisition systems. Acquisitionsystem differences can strongly affect (magnify or eliminate) measureddifferences in algorithm accuracy across demographic categories.

Some factors have differing effects on transaction times (Table 2) and,in addition to effects of reflectance, gender and age, biometricperformance also varied with volunteer height and weight. Forhigh-throughput biometric systems, small changes in transaction timescan lead to large changes in system throughput (e.g., reducing a fivesecond transaction time by one second increases throughput by 25%).Effects of height and weight on transaction times can be expected forthe tested systems since some systems adjusted camera position based onthe subject. Subject anthropometry may alter the speed with whichsystems adjusted to the respective subjects and the speed with which thesubjects used the systems. Differences in face angle associated withsubject height may explain the effect of this covariate on similarityscores. Taken together, these findings indicate that the acquisitionsystem, independent of the matching algorithm, can contribute to totalbiometric system performance across different subject groups.

Two images of the same person taken on different occasions may differsystematically with the passage of time due to face aging. Heredemographic effects on mated scores for images taken on the same dayversus on different days (1 month to 4 years) were compared. Gender andage covariates were notably found to be excluded from optimal models ofsame-day similarity scores. This finding suggests that faces of olderpeople in the sample may be more stable in their appearance over timerelative to younger people. On the other hand, faces of women in thesample are more variable over time relative to men, possibly due todifferences in hair-styling and makeup. That skin reflectance waspreserved as a covariate in optimal models of same-day scores arguesthat this effect, as expected, is a fixed trait of the subject andvaries little over time.

CONCLUSION

For any computer-implemented embodiment, “means plus function” elementswill use the term “means;” the terms “logic” and “module” have themeaning ascribed to them above and are not to be construed as genericmeans. An interpretation under 35 U.S.C. § 112(f) is desired only wherethis description and/or the claims use specific terminology historicallyrecognized to invoke the benefit of interpretation, such as “means,” andthe structure corresponding to a recited function, to include theequivalents thereof, as permitted to the fullest extent of the law andthis written description, may include the disclosure, the accompanyingclaims, and the drawings, as they would be understood by one of skill inthe art.

To the extent the subject matter has been described in language specificto structural features or methodological steps, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or steps described. Rather,the specific features and steps are disclosed as example forms ofimplementing the claimed subject matter. To the extent headings areused, they are provided for the convenience of the reader and are not betaken as limiting or restricting the systems, techniques, approaches,methods, or devices to those appearing in any section. Rather, theteachings and disclosures herein can be combined or rearranged withother portions of this disclosure and the knowledge of one of ordinaryskill in the art. It is intended that this disclosure encompass andinclude such variation. The indication of any elements or steps as“optional” does not indicate that all other or any other elements orsteps are mandatory. The claims define the invention and form part ofthe specification. Limitations from the written description are not tobe read into the claims.

Certain attributes, functions, steps of methods, or sub-steps of methodsdescribed herein may be associated with physical structures orcomponents, such as a module of a physical device that, inimplementations in accordance with this disclosure, make use ofinstructions (e.g., computer executable instructions) that may beembodied in hardware, such as an application specific integratedcircuit, or that may cause a computer (e.g., a general-purpose computer)executing the instructions to have defined characteristics. There may bea combination of hardware and software such as processor implementingfirmware, software, and so forth so as to function as a special purposecomputer with the ascribed characteristics. For example, in embodimentsa module may comprise a functional hardware unit (such as aself-contained hardware or software or a combination thereof) designedto interface the other components of a system such as through use of anapplication programming interface (API). In embodiments, a module isstructured to perform a function or set of functions, such as inaccordance with a described algorithm. This disclosure may usenomenclature that associates a component or module with a function,purpose, step, or sub-step to identify the corresponding structurewhich, in instances, includes hardware and/or software that function fora specific purpose. For any computer-implemented embodiment, “means plusfunction” elements will use the term “means;” the terms “logic” and“module” and the like have the meaning ascribed to them above, if any,and are not to be construed as means.

While certain implementations have been described, these implementationshave been presented by way of example only and are not intended to limitthe scope of this disclosure. The novel devices, systems and methodsdescribed herein may be embodied in a variety of other forms;furthermore, various omissions, substitutions, and changes in the formof the devices, systems and methods described herein may be made withoutdeparting from the spirit of this disclosure.

While some blocks/decisions may be captioned as “optional”, there is tobe no negative inference with respect blocks/decisions that are notdenominated as “optional”, i.e., blocks/decisions are not “mandatory.”In accordance with some embodiments, information is stored in memory (atleast temporarily) during performance of the methods for a variety ofreasons. Example rationales include, but are not limited to, dataprocessing convenience, communication convenience, permit batchvalidation/review, records maintenance, and so on, and combinationsthereof.

Although headings are used for the convenience of the reader, these arenot be taken as limiting or restricting the systems, techniques,approaches, methods, devices to those appearing in any particularsection. Rather, the teachings and disclosures herein can be combined,rearranged, with other portions of this disclosure and the knowledge ofone of ordinary skill in the art. It is the intention of this disclosureto encompass and include such variation.

What is claimed is:
 1. An apparatus for quantification of phenotypes inreceived captured images and remediation of image capture, for biometricmatching, comprising: a processing system having a hardware processorconfigured to perform a predefined set of basic operations by loadingcorresponding ones of a predefined native instruction set of codes, thepredefined native instruction set of codes constituting a set ofinstructions selectable for execution by the hardware processor; amemory accessible to the processing system; a communication controller,under control of the processing system, adapted to receive an indicationthat a first relative skin reflectance value derived from a first imageof a subject is outside of a predetermined range; image processinglogic, stored in the memory, comprising a respective sequence ofinstructions selected from the predefined native instruction set ofcodes of the hardware processor, adapted to calculate an adjustment ofone or more conditions for capture of a second image of the subject, asa remedial capture setting; image capture logic, stored in the memory,comprising another respective sequence of instructions selected from thepredefined native instruction set of codes of the hardware processor,adapted to capture the second image of the subject under the remedialcapture setting; and the image processing logic being further adaptedto: derive, from the second image, a second relative skin reflectancevalue for a face of the subject, and determine whether the secondrelative skin reflectance value is between a floor threshold and aceiling threshold.
 2. The apparatus of claim 1, further comprising theimage processing logic being further adapted to calculate a change ofgain of a camera, used to capture the first image of the subject andsecond image of the subject.
 3. The apparatus of claim 1, furthercomprising the image processing logic being further adapted to calculatean adjustment of a spectral sensitivity of a camera, used to capture thefirst image of the subject and second image of the subject.
 4. Theapparatus of claim 3, further comprising the image processing logicbeing further adapted to calculate an adjustment of intensity of lightfrom a light source, used to illuminate the subject during capture ofthe first image of the subject and the second image of the subject. 5.The apparatus of claim 1, further comprising the image processing logicbeing further adapted to calculate an adjustment of diffusivity of lightfrom a light source, used to illuminate the subject during capture ofthe first image of the subject and the second image of the subject. 6.The apparatus of claim 1, further comprising the image processing logicbeing further adapted to calculate an adjustment of a number of lightsources used to illuminate the subject.
 7. The apparatus of claim 1,further comprising the image processing logic being further adapted tocalculate a change of a background placed behind the subject duringcapture of an image.
 8. The apparatus of claim 1, further comprisingbiometric identifying logic, stored in the memory, comprising anotherrespective sequence of instructions selected from the predefined nativeinstruction set of codes of the hardware processor, adapted to perform abiometric comparison between the second image and gallery images, whenthe second relative skin reflectance value is above the floor thresholdand below the ceiling threshold.
 9. The apparatus of claim 8, furthercomprising the biometric identifying logic being further adapted to:identify the subject as an individual associated with a correspondingone of the gallery images most closely matching the second image, when aresult of the biometric comparison exceeds a matching threshold; andoutput an identity indication message indicating an identity of theindividual.
 10. The apparatus of claim 9, further comprising: anelectronic access control logic, comprising another respective sequenceof instructions selected from the predefined native instruction set ofcodes of the hardware processor, adapted to generate an access controlmessage, based at least in part on the identity indication message, theaccess control message instructing an electronically actuated accesscontrol device to perform an access control action, the access controlaction being to open, to maintain a state of being open, to close, or tomaintain a state of being closed; and the communication controller beingfurther adapted to transmit, to the electronically actuated accesscontrol device, the access control message.
 11. The apparatus of claim8, further comprising the biometric identifying logic being furtheradapted to output an identity indication message indicating an identityof the subject.
 12. A method for quantification of phenotypes inreceived captured images and remediation of image capture, for biometricmatching, comprising: identifying that a first relative reflectancevalue, derived from a first image of a subject, is outside of apredetermined range of reflectance and, based at least in part on theidentifying: calculating a remedial capture setting, communicating theremedial capture setting to an image capturing resource, upon receivinga second image of the subject, captured by the image capturing resourceunder the remedial capture setting, deriving from the second image ofthe subject a second relative reflectance value, the second relativereflectance value being for at least a portion of an image of a face ofthe subject; and determining whether the second relative reflectancevalue is within a window of suitable reflectance values.
 13. The methodof claim 12, further comprising calculating, as part of the remedialcapture setting, an update of at least one setting of at least onecamera of the image capturing resource, for capturing the second image.14. The method of claim 12, further comprising calculating, as part ofthe remedial capture setting, an update of a gain of a camera of theimage capturing resource, for capturing the second image.
 15. The methodof claim 12, further comprising calculating, as part of the remedialcapture setting, an update of a spectral sensitivity of a camera of theimage capturing resource, for capturing the second image.
 16. The methodof claim 12, further comprising calculating, as part of the remedialcapture setting, an updating of an illumination setting, forilluminating of the subject by the image capturing resource during thecapturing the second image.
 17. The method of claim 12, furthercomprising calculating, as part of the remedial capture setting, anupdating of a diffusivity of light from a light source for illuminatingof the subject by the image capturing resource during the capturing thesecond image.
 18. The method of claim 12, further comprisingcalculating, as part of the remedial capture setting, a change in anumber of light sources for illuminating of the subject by the imagecapturing resource during the capturing the second image.
 19. The methodof claim 12, further comprising calculating, as part of the remedialcapture setting, a change in a background placed behind the subjectduring capture of an image.
 20. The method of claim 12, furthercomprising performing a biometric comparison between the second imageand gallery images, when the second relative reflectance value is withinthe window of suitable reflectance values.
 21. The method of claim 20,further comprising: based at least in part on a positive result ofdetermining whether the second relative reflectance value meets thewindow of suitable reflectance values, performing a biometric comparisonof the second image of the identifying the subject as an individualassociated with a corresponding one of the gallery images, most closelymatching the second image, when a result of the biometric comparisonexceeds a matching threshold; and outputting an identity indicationmessage indicating an identity of the subject.
 22. The method of claim21, further comprising instructing an electronic access control deviceto open based, at least in part, on the identity of the subject.
 23. Themethod of claim 20, further comprising requesting non-automatedidentification of the subject when the biometric comparison with all thegallery images is below a matching threshold.